Worst "at-gate" downgrade story I ever had, I was flying JFK-LAX. Had been upgraded to J in the Admirals Club on a late-morning flight after being cleared off the standby list. BP in hand, I made my way to the gate. GA took my BP, apologized and told me "another passenger with higher status checked in," and gave me another BP for the first row of MCE in Y. Flight was fine, I enjoyed my free BOB food and drink and stretched out my legs. No big deal, I never asked for compensation or wrote in because I felt like I wasn't due any or didn't need to say anything, but I've always been curious as to why I got booted from J. I guess I lost my seat because I was standing by for an earlier flight, but I've always wondered.