I was flying home from CAST 2010 yesterday, and I found a bug. (Guess those testing conferences wear off on you!) I was on a two-part flight (Grand Rapids -> Baltimore -> Boston), and had upgraded to an exit row seat on one of them, at a cost of $20. The second flight was a standard seat.
This is what the terminal showed me when it came time to pay for the upgrade:
For the record, I was only charged $20. Go Airtran kiosk!