High Usage Early A.M.?

We have a dual fuel system and with the cold weather the backup/aux is running as the primary which is propane. (Switches over at 34 degrees)

We are about two weeks in using the lite and overnite we have the stat set to 64 degrees and wake up time of 7am with preheat at 6:30 to 67 degrees

Been noticing weird spike in usage at 4-6am or so. Any ideas? Would this be the preheat — seems excessive