I am certainly not complaining. This was probably the single-most pleasantly surprising experience I've ever had with AA, but my curiosity is getting to me and I'd love to know WHY I was upgraded. I was returning on an award ticket on flight 99 (LHR-ORD). Since I had only booked the 60K award ticket, I didn't even have delusions of a possibility of an upgrade. After checking in at the gate, I took a seat to wait to board when suddenly I heard an announcement with my name, telling me to come to the front desk. I did so, and was handed a new boarding pass, and told that because I was platinum, I was upgraded to business class. I looked at the gate agents in disbelief but with a giant smile, thanking them. They simply responded it was nice to put a smile on someone's face every once in a while. I had a lovely trip home from there, and am greatly appreciative of this gesture. I'm curious though: why was I upgraded? There are platinum members all over the place. Certainly they don't upgrade all platinum members ordinarily - did they need an econ seat to give someone and began upgrading first ExPlats and then Plats? What happened?