lately my son has been grinding his teeth is there any way I could teach him not to??

my daughter does too! i noticed it last month. then 2more teeth popped through. and she's started it again which makes me think there's more about to cut.

I'm just worried if he does it too much he might chip them or something

Unfortunately no, I asked about it and there's nothing you can really do, but it is totally normal. I always looked at my daughter and told her no and put my finger in her mouth to stop it. She quit, but they eventually quit on their own usually.