The answer is the deer heard you but did not see you or smell you. The stomp was for you to identify yourself and the single blow was an alarm for POSSIBLE danger. If the deer had actually seen you and smelled you it would have kept blowing into the next county. You should have stayed because the deer would have returned in an hour or so to try to identify the intrusion. Sometimes you can answer the stomp with a blow or couple of contact grunts and the deer will many times just wander away quietly. Also raking your feet in the leaves with and light bleat or two will put them at ease. The main thing it should tell you is either you were not getting in early enough or it is a feeding area at time of morning so a change to afternoon hunting there or change your access route to that stand. As long as you don't make that mistake again at that location you should be OK.