Sitting (kinda)

Luke has started sitting a little. Being a first time mom, I'm not sure if this really counts as sitting. Is it really sitting if your belly drags the table? Whatever this is...he can hold himself like this, unsupported at 4 1/2 months. I have to keep a hand close by because he will fly off to the right or left at times with very little warning. This position is hard work. It makes his mouth hang open and gives him significant difficulties with saliva management.