My coach sat behind us at the movies didnt know until movie was over ?

my swim coach sat behind me and my boyfriend at the movies well we were at pirates of the caribean the new one and we sat very close to the back wel we did not see our swim coach come and sit behind us well the movie started and we started kissing we were making out the whole movie when we got into the lobby we were waiting on our friends to get out and our coach comes up to us and says hey kids looks like you to where having fun o my god i see him every day for 4 hours for pratice what do i do to make this less ackward