My son will not stop ducking his fingers and hands. Hes at the age where he should be trying to grab things but when we try to put things in front of his face he just looks and sucks his fingers. He wont try grabbing anything at all. Hell be four months next week but I'm just getting scared cause my moms saying he should be trying to grab things and rolling over. Any tips? We do tummy time for about 20 minutes every day and he can sit up in his bumbo seat.