my 14 month old doesn't chew his food

Our 14 month old son got sick last night from having a fit and crying so hard, when he threw up we noticed a good amount of his shells and cheese (dinner) we're whole, and not chewed! I'm curious is chewing supposed to be a natural reflex for them or is it learned? Should I be doing more to teach him? I do try to show him and say chew when he is eating, but this explains why he only prefers puréed food- easier to swallow... has never liked things like pancakes or sandwiches although I do offer them somewhat frequently... if I open a banana he will come over and take bites until he's satisfied... I'm overly anxious because everything I've read on the internet suggests this could be a sign of autism which, my husband has a sibling with a son with severe autism and I have been very paranoid that it could run in jos family... of course we would want to get him help as soon as possible but it can be very hard to tell before 18 months his pedi told us although he seems to be hitting most milestones in the right time. My main concern in this post is the chewing, or lackthereof, can any moms shed some light on this for me? Is this normal? What should I do?!