My 11 month old is walking, babbling, and smiling/making eye contact. my only concern is that he doesn't do hand gestures. is this an autism concern?

Not at all: In fact, the babbling is far more important, and many children develop pointing and gesturing skills closer to 13-15 mos of age.

Not necessarily, but: It is a social/adaptive delay if he doesn't imitate pat-a-cake, peek-a-boo, wave "bye-bye" back when someone waves to him or turn consistently when you call his name. Tell his pediatrician so he/she can do a thorough physical exam, including vision and hearing. You can find developmental screens at firstsigns.Org. An isolated delay does not = asd, but it should be checked out and monitored.