Checking 1B prior to set, heel comes up
 

This looked weird to me in a PONY (OBR) game with pitchers and coaches still a little weak on balks. The pitcher prior to coming set checks 1B with a shoulder turn. This pitcher while turning to look at 1B lifts his pivot foot heel about 3 or 4 inches when he does this. I told pitcher and coach don't do this or I will balk for a feint. He managed to turn without lifting after that. Am I offbase?

He can do this prior to coming to a complete stop. Once he has come to a stop, he cannot do anything besides step towards and throw to 1st or step backward off the rubber with his pivot foot (and then do as he pleases) or deliver the pitch to the batter. Any other little twitch after coming set is a balk.

Your job is to call a balk if and when he balks.

Way off base!
This is not a feint or a balk. Stop coaching, you are an umpire!