He is still young and young birds can be clumsy at times. That having been said, I would not dismiss it. Definitely get him to the vet just to make sure there is nothing underlying that caused the fall and no injuries resulting from the fall.
You were probably bitten because he was scared and shocked, kind of like if someone says "are you okay, are you okay?" right after you injure yourself and all you want to do is scream in their face lol...or is that just me? haha
Also, you guys are still building trust, while young birds tend to be sweeter than mature birds, you haven't had him for very long.
TAKE-AWAY MESSAGE: Get him to the vet ASAP, just to make sure all is well (he may be totally fine, but you need to verify rather than assume).
Also, if you haven't done blood-work, you should consider a CBC at the very least because birds hide illness and sometimes, we have very few indicators (as owners) other than test results.