Was on an AA flight diverted mid-flight due to weather at LGA. AA rebooked me on US Airways. US Airways required me to pay their baggage fees and said to seek compensation from AA; I had already paid AA their fees. Shouldn't AA pay, since I shouldn't have to pay a double baggage fee just because they re-booked me on US Air?

AA also colossally screwed up the re-ticketing--zero communication between 800 number and the ground ticketing agents--but we'll leave that aside.