No, it's not weird - especially if you two are apart. I was once in a relationship with a girl where distance separated us a few times. She mailed me a pair of her panties and a shirt with her perfume on it. I asked her specifically for the underwear, not anything else. Asking for a few pictures is a bit more tame in my opinion. Go for it, man. Just explain that you don't like being apart, that you miss her and that you want something to remember her by whenever you're yanking your chain.