Leaving Money on the Table

I just happened to check some of the stocks I shorted the last couple of weeks to see where they are at today. Here is one in particular that makes me frustrated. I bought puts on AM when it was around 18 and sold them when it fell to 13.50. Granted I made a 250% return but looking at the same puts I owned, I left a couple grand laying on the table. Morale of the story, things can always go down more than you expect.