http://www.alaskajournal.com/stories/082808/hom_20080828001.shtml
She was in Anchorage at least on Wednesday.
“Palin signed the bill during a noon speech to Alaska labor leaders in Anchorage.”
Yes, that signing ceremony was at Noon. The flight to Flagstaff, Arizona (via Seattle) was at 2:15 PM. Plenty of time to have the ceremony and get on a flight.