Oo naman, totally normal yan sa 16 weeks! Baby's movements are still so light kaya parang usli lang talaga or bubbles, hindi pa yung strong kicks na mararamdaman mo later, a few of my mum friends said the same thing, parang parang gas or butterflies lang daw sa una. But if you're worried or natanggap mo lang ngayon yung movements at gusto mo lang ma-confirm na lahat okay, definitely check with your OB just to put your mind at ease, lalo na since first time mo pa lang mag-feel nito!