Asking for help from feloow umpire

[St. Louis Blue]

I had this situation last night. R3 Pickoff attempt by F2. Throw is on the outside of the sliding runner. I call out. Base coach says the ball was loose. I didn't see it because I was screened by the runner. I asked PU if the ball was loose, he said yes. I rule Safe on the drop. According to the PU after the game, the ball dropped out onto the ground as the tag was made but didn't go anywhere. F5 re-acquired the ball immediately and came up with it to show me. My partner is very experienced and I have great faith in him. If he tells me the ball was loose, I believe him.