Holding the ball

[LilLeaguer]

OBR, Rule 2.0:

A TAG is the action of a fielder in touching a base with his body while holding the ball securely and firmly in his hand or glove; or touching a runner with the ball, or with his hand or glove holding the ball, while holding the ball securely and firmly in his hand or glove.

In a game last night, F3 received a throw from F5 at the dirt.

1. Picture F3 touching 1B with his foot, and the ball held between both sides of his glove and the dirt.
2. Two steps later, B/R crosses 1B.
3. After a significant pause, F3 lifts his glove, holding the ball.

Since F3 made no adjustment before lifting his glove, I judged that he had had the ball firmly and securely in his glove (though in contact with the ground) before the B/R crossed the bag. I rang the runner out.

Is this the conventional call, or does contact with the ground preclude a secure holding? (My call was somewhat controversial with the 1st base coach, I think. Not that I noticed his reaction or anything.)

-LilLeaguer