C.G.
Honestly maybe its from the confusion of moving, siblings, etc. my twins 4.5 yrs old did the same thing and I don't know if it is a boy thing but they don't seem to as coordinated as my 9 yr old daughter. My mother in law said all 4 of her boys did it too. I wouldn't worry just yet. Just try to break him of the habit and if it doesn't work I'd ask a dr.s opion. They all have suggestions. Oh and my boys still do it, that and first fight. LOL. Hope that helps. You are not alone.
C.