I should've known better...
ATL-PHL last week. Bid $500 at kiosk. Got to gate and asked agent if she needed volunteers - she said looks like they won't, but asked for my seat number anyway.
Went to grab dinner, came back, and it appeared that they were clearing a bunch of people from the SB list already so I boarded with SKY and took my seat in FC.
Halfway through boarding, GA comes on and says she didn't want me to board and if I was still willing to volunteer. I said yes and she said she'd come get me.
Boarding finishes, GA comes back on, and says she didn't need me after all as there were a couple people who hadn't boarded yet that she was able to use.
Kudos to the GA for coming on board to check and keeping me informed, and of course I'd expect that she'd VDB the folks who hadn't boarded yet. But I'm still kicking myself from not stopping to ask her a second time before I got on the plane...