Sounds like spacing to me.
Looking at today's (Nov 3) first few AUS-LAX flights on AA, WN, and UA:
AA 145 / Sked DEP 7:15 AM / Act DEP 9:07 AM
UA 5653 / Sked DEP 7:20 AM / Act DEP 8:12 AM
WN 180 / Sked DEP 7:50 AM / Act DEP 8:51 AM
AA 5930 / Sked DEP 2:55 PM / Act CANCELED