Maryrrf, that's what I'd expect. (I find that what's allowed and not allowed on a plane as carry-on similarly varies with which agent is at the gate and what mood they're in.)
Having a longer wait at the airport isn't all that bad at PDX (or San Diego) because of the free wireless internet. I can sit in comfort and get lots of stuff done. (Even without the internet, if you have a laptop you can get a lot done.)
Thing is, this time I need to decide by today whether to cancel/reschedule a flight. I can't wait till the day before because if I'm going to cancel a gig (which I probably can't make with the current flight schedule), I need to give them time to find a replacement. It's been very, very rare for my flights to be completely full in the last year or so, especially at this time of year, but I'd like to know if the airline is usually willing to allow this when they have room.
I guess I can call Southwest, but this may be something that they just do sometimes - even often - without it being official policy.