Hey momsh, yan ay totally normal sa 6-month-olds, lalo na kapag pagod na pagod na sila or ready to sleep, ang trembling na yan ay sign lang na relaxing sila habang nag-feed! Pero since umiiwas ito kapag hawak mo, baka comfort lang talaga kailangan niya or sleepy movements, kaya maganda kung mag-check ka pa rin sa pedia mo para peace of mind mo lalo na if it looks different or may other concerns. A few of us moms na kaibigan ko noticed din yan sa babies namin, especially towards nap time, so you're not alone dito! Keep an eye lang kung may ibang signs, pero kung ganyan lang talaga siya and happy naman siya overall, likely just one of those funny baby things na mangyayari lang.