Had something similar to this happen once before. Was calling 11U USSSA ball and as the PU had a play at the plate. The ball clearly beat the runner but the throw was low and the catcher caught it between his legs while on his knees in front of the plate. The runner slid into the catcher and his glove and immediately I said, "show me the ball" (there were no other runners on base), but the boy did not do is so again, immediately I said, "Let me see the ball", and the second time I asked the boy started fidgeting around between his legs, which IMO it made it seem like he was trying to either get a grasp on the ball or he was trying to find the ball so immediately I called him safe and pointed to the ground.
Well, the coach(es) for the defensive team didn't say a word but the owner of the team on defense (which from what I have heard from many other umpires and now from personal experience, is a complete ass and doesn't know the rules of baseball) comes out raising hell and wanted a protest and all. This was my first USSSA ball game to call so I didn't really know how to handle the situation.
I clearly should have tossed the guy because he made a complete ass of himself and basically tried to make one of me too. About an inning later we had a play at second base where the boy tried to turn a double play (against the team that was in the field in the above situation) and when he caught the ball at second and went to relay it to first he lost the ball. This was clearly "on transfer" and the BU got the call right but the RAT came out again and before he even got 2 feet across 1st base the BU tossed him! Just what the doctor ordered.