2.5month old active tongue (thrusts, smacks, sticks out) starting to interfere w/ bottle/paci/nipple latch. gags often. normal or cause for dr visit?

I'll pick a visit: Since the interference is causing possible nutrition deficits - it sounds like a good reason for a visit. The cause may not be serious, but the effects are. Also, if there is a problem requiring attention, this will perhaps identify it. Develop a good relationship w/ a pediatrician - it will benefit both your baby and you. Best wishes for you and yours!