My father in law was convinced that my daughter was deaf, despite having had her hearing checked by a health visitor. I knew better as she could hear the biscuit tin being opened fron a different room and would come in running, shouting "Want one" She has no hearing problems, or indeed any developmental delays but was just very independent and refused to perform party tricks for her grandad!
I had the opposite problem with my youngest son who did have a number of issues after being very poorly with meningitis when 6 months old. The long stay in hospital resulted in him regressing a little ie back on baby formula after beginning weaning and no real speech until turned 2. But this same man refused to accept that his grandson had any problems and thought we were fussy parents for taking him for regular checkups! Luckily there were no lasting problems and he was finally discharged when he was six - ironically his sister, just 13 months older who Grandad thought was deaf, doted on him and it wasn't until she went to school full time that he was allowed to speak for himself!
I was too laid back to be cross with my FIL but he really should have kept his pointless comments to himself, we were well aware of how our own children were developing.
Yes, the original poster might have concerns, but please keep them to yourself for a year or so, it's amazing how much toddlers develop in a short period of time.