Thanks everyone. Sounds like I'll just take it to the dealer and get the battery replaced.
As an engineer, this seems like bad system design to me. I don't see why the battery management system can't detect a sudden change in battery characteristics (as would be evident in a battery swap) and put itself into a learning mode that figures out what would be optimal for the new battery (instead of retaining what it "knew" about the old battery). Oh well... it is what it is I guess.