absolutely not, just make sure you keep your practice up. its a difficult skill. i started when i was about 13, took me a while to get my first tricks, but once you get the swing of things you're golden.
its also important to stretch before you go out, make sure you keep your bones strong, and overall health very good. getting hurt sucks and its best to keep your muscles and bones strong!
skateboarding is very aerobic, so this is good! skate or die trying man. its a blast, i'm 20 and i still skate at least every other day.