My son started doing this "shiver" looking thing around 4 months of age. Ped said it was normal, just his nervous system still developing . As long as he's still conscious while doing it, eyes remain open, you can distract him, call his attention, it's probably not a seizure. But look into it with his doctor anyway like the other mamas said!

I've seen all babies do it. They're just figuring out their movements. Like oh i didn't know I can do this You know? Lol but like those girls said, if you want a piece of mind take him to a doctor (:

It could be perfectly normal but it's always best to just consult your Dr so you can have piece of mind.

You should contact your Dr and just check with him.