Started seeing a girl recently, found out she's older than I thought, what to do?

Quick summary: Been on a few dates before xmas, then a break, then seeing her again now were back in the same city. Though she was 21, but she's 24, doesn't seem like a big difference, but in my head the dynamic seems to have changed. Im predicting a few answers along the lines of 'be yourself' and whilst that's very helpful, and she still seems interested, the age is all I can think about at this tenuous early dating phase. Beforehand it was easily to be the 'guy' in the relationship if you know what I mean, now Im just questioning it all. Not dated any older women and whilst 4 years doesn't seem like a lot, it is when your 20! Im kind of aware now that she's had all this extra experience and been places etc (living longer does that I guess :P), I guess I thought I had her mostly figured out and this has just confused my picture of her. So yea, anyone got any ideas about how I can push the age to the back of my mind? Any tips on dating marginally older girls also appreciated and I think I'm out of my depth as I've resorted to asking good ol' mr internet. Cheers guys!