Quick question, does your baby necessarily have to wave hi and bye at 9 months? I was at his doctors yesterday and one…

Quick question, does your baby necessarily have to wave hi and bye at 9 months? I was at his doctors yesterday and one of the assistants asked me if he does and I said no and she acted like it was "concerning". My son is at all the milestones for his age he's even a little bit ahead with everything else. I've tried to get him to wave to me and his dad and he just doesn't wanna do it lol.