Is the five year age gap between 18 and 23 too big?

there's a guy in my chemistry cl that i've had a bit of a crush on all semester. we didnt talk much, but last monday, we were igned as lab partners. we got to talking about the book i was reading, and we clicked pretty quickly. however today, we started talking about drinking (after he invited me to his party, hooray!) and i realized he's 23, and i'm still a little 18 year old who has to scheme and plan for hours to get one bottle of decent alcohol. i act really mature for my age, since i'm a bit of a genius and started school two years early, but do you think he views me as too young?