If your hamster is from a pet shop she sounds to be one with a lot of Winter white in her.
There hamsters change from a browny grey to an almost white hamster in the winter. Even if it is not that cold the change is light levels can trigger the coat to go in to winter coat. Sometimes they just get patches and sometimes they change fully then back in spring. There are some pics here of one who has changed :
My hammy is changing colour....
Don't worry about it as it perfectly normal