Nighttime Grunting

Starting at about three weeks, Baby CP started having episodes at night during which he would grunt, squeal, kick and twist arms, legs and body all over the place.  The weird thing is, he is asleep while he's doing it.  It started the couple of days that I tried to introduce a bottle, so I blamed this new development on the bottle.  I haven't really used a bottle since then, but last night, the grunts came back.  Some internet research tells me that it's normal behavior that will clear up over time, but when Mr. CP and I watch our little one go through it "this can't be normal" runs through our minds.  Poor thing...