From what I understand the TSA is interested in it being a valid boarding pass for the day you are flying. They don't, nor would I expect them to know every airline or flight from their airport.
I think one of the TSA supervisors told me its the date that is important. Before I quit smoking I used to go in and out of security at every non-smoking airport I transferred through. Flight delayed? No problem - outside for another smoke. Even the airports that initialled my boarding pass didn't hassle me when I went through security again with the same BP. If they asked I just told them I was out for a smoke. Never had a problem with this.