Agree with HH, give him a few days to settle down as like anybody in a strange new environment they do need time to adjust to their new surroundings, don't forget he came in the dark, was shut in a stable and then let out on new ground so he's bound to be a bit grumpy. Keep a board and stick handy, if he goes to bite dab him on nose end, as male he will try to make himself boss(they all do!

) Secondly I suspect when you went in the field he was expecting treats, ask the previous owner if she often carried treats in her pockets, we have an old boar (9+) and he likes to be boss and he does try to chase me sometimes so I've taken to shoving a large apple or carrot in his gob and that sidetracks him, but now he expects a treat all the time so rod for my own back!

Anyway see how you go, try not to let him now you're a bit wincy about him or he'll sense it and BE careful.
all the best mandy