Yeah it is strange behavior but not unsual my oldest male normal boa does it
hes about 3 also he likes to stretch up and push as well when he was smaller he did it but he will fall over because he couldnt reach and some strange reason during the cooler season he does gets hissy and im surprised how much louder they hiss over bp's....he should be healthy i tend just to take him out when he gets all ansy and doing that..
Good Luck