Catch or no catch

[IndianaGeorge]

Had the following last night while I'm umping behind the plate: Short pop fly near the foul line. Pitcher makes a diving catch, rolls over and lands on his back. As he raises he glove to show me the catch, the ball pops out.

I signaled out, explaining to the offensive team's coach that I felt the player had possession and the ball came out when he was showing me the catch.

After reading Rule: 2-9-1 on a catch, I'm still not sure if I interpreted it correctly. Is the player showing me the catch considered "continuing action of the catch"?