I flew SFO-BUR this week, and a deadheading flight attendant from another airline was told to gate-check their bag.

The crew member had a personal bag and the flight attendant combo bag (the bag that attaches to the top of a roller-board with a strap), which the gate agent managing boarding said counted as two bags. The crew member got upset and appealed to the agent at the desk, who backed up the other agent. He ended up gate-checking his roller-board-and-bag combo to make his commute.