The next day she thought nothing more of it - until the following week, when the same thing happened.
Mrs Grimmer thought to be on the safe side she would visit her doctor.
Despite having had regular mammograms since she turned 40, and a clear mammogram four or five months earlier, Mrs Grimmer got the news every woman dreads.
There was a lump in her breast.
Mrs Grimmer was diagnosed with breast cancer at the end of April 2008, by the end of May she had had surgery and at the beginning of July she began chemotherapy, finishing her treatment three days before her 49th birthday.
After the chemotherapy, Mrs Grimmer spent five weeks in Dunedin having radiation treatment, describing her life for that year as "like being on a treadmill".
"Your life is scheduled around treatments, appointments; everything's structured.
"At the end of the treatments, sometimes people go, `What now?'."
It was a question Mrs Grimmer asked after completing her treatment and starting on the road to recovery.
In August, she was in Auckland and her husband picked up a copy of the Queenstown Times, featuring an article on The Studio Pilates and Physiotherapy's Pink Pilates Trust, run in the Wakatipu by Louise Parker.
The Pink Pilates Trust, supported by the Breast Cancer Foundation and funded by voluntary donations, helps women diagnosed with breast cancer regain their physical strength, improve their body confidence and incorporate exercise into their lifestyle through a combination of manual physiotherapy, clinical Pilates, massage and breathing techniques.
When Mrs Grimmer returned to Queenstown, her husband showed her the article.
She signed up with Ms Parker.
"It's great, because Louise talks through everything with you; there is no pressure. It's quite a relaxed feeling really.
"From Louise's point of view, because she's so professional, she's going through all the things in your body that are different . . . it's just to make you aware of what you can do.
"You lose a lot of confidence and doing the exercises, doing the Pilates, it's good to know . . . you're only limited by yourself.
"You have just got to get out there and get back into it."
Ms Parker said since she began the Pink Pilates Trust programme about 10 women had completed the one-on-one programme.
"Some people say, `That's not many'.
"But we're a small place and we don't want that many women coming through.
"It's great to be able to help but it [breast cancer] is not something you want someone to have.
"There are a lot of people who get to the other side. We call them survivors."
Ms Parker said each woman's programme differed, depending on their treatment.
While some women may have had a mastectomy, others may have had partial lymph node removal, or full removal.
Even radiation therapy could limit movement in the arms because it caused scar tissue.
For Mrs Grimmer - who recently returned from a holiday where she swam in the sea every day - the programme had given her life back to her.
"I feel good now.
"I was very fortunate to have an amazing family . . . and a close network of very good friends.
"That's the most essential part, to have that support.
"It doesn't mean they're ringing you up all the time . . . it's little things like texts saying, `I hope your treatment goes well today'," she said.
"It's all about attitude; that's what a lot of people have said to me.
"I've been there, done that and come out the other side."
To breast cancer patients, Mrs Grimmer has some advice: "Don't live in fear, but be careful about your choices."
Because her immune system was weakened during her treatments, Mrs Grimmer was advised to avoid places with large numbers of people, such as supermarkets and picture theatres.
However, she took advice from her brother and did not touch her eyes, "because that's where most infections enter the body", and she lined her nostrils with vaseline.
"I did and I was good as gold.
"I didn't even get a cold during treatment."
Now Mrs Grimmer, who recently "proudly" celebrated her 50th birthday, is gearing up for another challenge.
She wants to complete the Real Women's Duathlon, which is being held at Millbrook in March.
Visit www.pinkpilates.co.nz for more information on the Pink Pilates Trust.
The Studio is also selling the "Pink Pilates top", designed in conjunction with MaxBody, part of Max's new sports-luxe collection.
All the proceeds from the tops go directly to the Pink Pilates Trust.
The trust is responsible for allocating funds to women in the Wakatipu.
Since its launch in 2006, Pink Pilates has helped more than 500 women in New Zealand recover from the effects of breast cancer treatment.
The tops, which come in pink and black, cost $60.
They can be ordered through The Studio.
