I was catching Keystone 649 at PHL around 4.30pm this evening, and it was announced that customers for stations to NYP with reservations for 148 would have their tickets honoured on Keystone 652 without additional charge.

I also found myself with a ticket for a heavily delayed (around 3 hours, but not cancelled) train 66 back from DC one Sunday evening, and was reaccommodated on train 90 (advertised as "set down only" at DC under normal circumstances), again without any fare difference being collected.