My almost-4-month-old is thumping her arm..

[Aberrance]

My DD has recently started raising one arm up, then thumping it down to her side, sometimes thumping whomever is holding her, or even her own leg. It's a very rhythmic thump, she's always on beat.
It's usually her left arm, but she'll do it with her right also.. And sometimes both arms at the same time, but alternating. Thump right, thump left, thump right, thump left...
It's a little odd. She's not upset, it's more often when she's in a good mood. And she's not excited, she'll do it as we play video games, or watch a movie.

Does anyone else's LO do this? Does it mean something that I'm too thick to follow, maybe?

 

[Geminski]

Hiya my lo is 3 months and she does this in her cot when her cot mobile is on but never when people hold her id say its pretty normal and mabye its just an excitment thing x

 

[nicole_]

my LO does it all the time, we say he looks like a flappy penguin
he mainly does it with one arm and proper slaps himself, does it even faster when hes excited but he does it all the time when hes just playing on his mat
i think its just because they cant fully control there arms yet so a big movement can turn into a big flap

 

[Aberrance]

Yeah, it is rather penguin-y! Haha.. I wonder what she's thinking as she does it.. Maybe I'll get her a bongo.