Aiyoh, I haven't felt that before but a few of us mums have mentioned random twitching sensations months after c-section, so you're not alone! Since it's been 9 months now and you're noticing it under the scar area, best to check with your gynae just to put your mind at ease, could be scar tissue settling, nerve stuff, or even just your abdominal muscles doing their own thing postpartum, but doctor can confirm lor. The fact it's not painful is a good sign, but definitely mention it during your next checkup!