Yikes, that would bug the heck out of me. Unless, it ended up under the table somehow, I am pretty positive you didn't leave it on registration day at Coronado. We were pretty close to the last people out that night, and my Dad and friend were siting where you were after you left.
Here's hoping it is in your house, just in one of those completely random, "how the heck did I ever do that!" places. When we moved from WA to AZ we had a few things we thought were lost forever. 5 years later when we moved from AZ to CO we found a box, in the back of a closet that we had never opened, with all the stuff we were missing.