Changing Calls?

[IamMatt]

Curious about a couple of calls I have seen recently (ASA 12U), and whether it is normal or typical to change a call.

1) BR grounds to F6, throw to F3 beats the runner, Ump calls "Out." Offensive coach calls out "Her foot was off the bag!" Ump says, "You're right, she's Safe!"

2) R1 stealing second, F2 throws to F4 covering 2B, F4 lays the tag down as R1 slides into 2B, which knocks F4's feet off balance just enough that she is supporting some of her weight on her feet and some on her hands on the runner (preventing her from tagging and raising her glove since she is leaning on it). Ump calls "Out!" 2-3 seconds after the call, as F4 rights herself, the ball comes out of her glove. Offensive coach calls out, "She dropped the ball!" Ump changes call to "Safe!"

My question comes from a point made recently in another post, which was basically, "If you didn't see it, don't call it." And in the ASA rule book I believe I have read that you don't "guess" on outs.

I would think in either case, if the ump called it, he must have seen it, so it seems odd that they would change the calls like that. Any thoughts?

BTW, no, in neither case did the coach ask the ump to check with his partner, nor did the ump do so on his own.