I'm sorry if this has been asked before but I can't seem to find a search button.

My g/f is holding the return part of a r/t domestic award ticket booked in econ. She called to change to a later departure and was told that although time changes are normally free, she would have to pay $100 because it's connecting through a different city (her original flight was SAN-ORD-DCA, she's trying to do SAN-SFO-IAD, and no, the agent didn't say the problem was with a different arrival airport, but rather that the connection is at SFO instead of ORD).

Is it really so? I thought it didn't matter if you chose a different routing so long as origin, destination, and any official stopovers remained the same. Does a different rule apply to changes on award bookings?

If anyone knows, please let me know ASAP as award inventory on this date seems to be very low. Thanks for any info!

Yonatan