Having boarded my economy seat on an AMS-ATH flight recently, an FA came up to me and asked if I would like a seat with more room. I thought I was getting a Platinum upgrade to biz so I lept up...only to find her standing well behind me in the exit row. It was appreciated, but I can honestly say I've never had such an op-up.

On the return I got a proper op-up to row 2.