Gate AAgents may not know everything that we know!
Last year an AA (mainline) Gate AAgent was checking me in on standby for an earlier flight. I asked about getting an upgrade. She then asked 'do you have stickers for the upgrade?'. My response was 'oh as EXP the domestic upgrades are complimentary'. To which she repeated NO.
I then suggested she check with a supervisor before doing anything and went to the AC.
Upon returning the gate I was handed my First BP and the AAgent said 'you were right'.