Don't worry about it! I've been in the same position as your girlfriend and honestly, as far as my (and my other friends') experience goes, you leave the pictures there because you don't want to just completely erase a whole period of your life, NOT because you're not over the guy. (Alternatively, maybe the colours/filters of the picture just look good on her page lol.) I still have the pictures of my boyfriend from almost three years ago on my Instagram, and I assure you I don't feel a thing for him. We haven't talked for years and don't even live in the same country anymore. But I don't want to be scrolling through my timeline and there's this massive void where I've erased my life because I no longer like the person who shared it. So don't worry!!!!With regards to what you can do, if it REALLY bothers you don't let it fester - communication is important. BUUUUT, personally I wouldn't mention it at this early stage in the relationship. See how things go. When you've been together a while, bring it up directly and politely. She probably won't have even realised how it makes you feel