if she has great boobs maybe she wants to remember them the way they were, if (hopefully it wont come to it) theres a mastectomy on the horizon then reconstructive surgery often follows....
so maybe shes hedging her bets, so if theres cosmetic work done later she can whip out the pics and say she fancies another pair just like that or a couple of inches higher bigger whatever.
mastectomys can be defemising, some women feel like theyre not whole after so maybe its her way of reminding herself that she was is and will be just as much a woman when its all over....bit like a personal goal thing.
who knows, but no i dont think its weird.