Maybe, maybe not. If that's the ONLY time it happens, then it may pass - like PP said, he might just be excited and the novelty will pass.
Keep your eyes open and see if it happens at other times, or if there are other situations you would describe as "overstimulation," maybe think of this as a flag (not even a red one yet) to keep your eyes peeled.
Meanwhile, what happens if you put something IN his hands, like an extra diaper, or a wipe, or a small stuffed toy? Does he flail it, inspect it, throw it, whatever? Might be finding new uses for his hands!
Josie did well with a small blanket, like 12" square or so, so caress, which she could also use as a lovey for sleep times.
Just a thought!
Edited to add: Make sure he gets lots of tummy time! When he flails his arms on his tummy, eventually he'll accidentally (at first) get them under himself and either lift or move himself. SO cute when that happens!!!! If you can watch his arms and legs when he's on his back, imagine a turtle on its back, and then what happens when you put the turtle back "right side up!"