FA timed out. We had a MX thing just as we were about to push from the gate on the way to COS that held us up (we were already running late due to a last second captain change, not sure what happened there). When we got to COS, the FA told us she didn't think she was legal to do the return...Scheduling confirmed this and we ferried back, despite my pleading to hang out in Colorado Springs. It was a shame( and probably preventable), I heard the paxs in COS got really really upset and wanted to riot at the gate.