So what was fascinating in my case was I was asking at the UC club and the agent (yellow scarf) didn't catch that I was GS originally. I could tell she was working hard and just not finding anything (mine was like the third flight to ORD cancelled so I believed they didn't have a ton of space). At one point I asked about other carriers and she said "Oh no, not for weather" to which I reply "even for GS". Next thing I know she has me on the next flight and heard her tell someone they oversold for me.