Oo, maraming babies ang may head bobbing or slight tremors habang kumakain, lalo na kung excited sila or concentrated sa pagkain, pero since your baby's 6 months na, mas okay kung i-check mo na lang with your pedia just to be sure, para matulog ka ng mahimbing at walang alalahanin. A few of my mum friends had the same worry, and most turned out it was just enthusiasm sa pagkain, pero better safe than sorry talaga, especially pag first baby!