i would get him home and watch his behaviour, he could just be doing it because of a diffrent enviroment, diffrent people ect.
we had our 2 dogs at my mil's while we moved and had to bring them home sooner then planed as they started to fight constantly, they were going ok here untill bil came over and stirred them up. it turned out he was starting the fights at mil's house and untill he started them here they were fine.
good luck, but i would keep a close eye on him and hope it was just him having to prove his place at your aunts.