Feet or ball position on out of play

[DaNewGuy]

I had a similar situation in 16u slow pitch tourny this weekend.
Drive hit toward first base. Ball hit fair but spun up in the air about 3 feet and would have landed foul before first base. First base player gloved the ball with right foot clearly in fair territory and left foot in the air above foul territory. Ball was clearly under control before the left foot came down in foul territory. My call was fair ball - there were no arguments from anyone and the call was accepted, but there was dead silence and a lot of "chatter" among players, coaches, and fans. I guess no one knew what happened or saw it before. Correct call?