Ankle popped today in class!

Hey guys.. Has this ever happened to you?  I was mounted on my opponent and climbed higher to go for a triangle choke.  I pulled his head up and whipped my leg behind his head then paused for a second.  He bridged up and turned toward my foot and rolled me over but as he did my ankle made a huge pop sound.  It didn't hurt but everyone in the room freaked out at the sound.  I laid there and rotated my foot around to check and felt no pain at all.  I thought however that once I cooled down it might swell up really bad.  It's the end of the day now and that hasn't happened.  Am I in the clear?  What could have made that sound?  Thanks.