My bf of 5 months never................?

we never hold hands, kiss, cuddle, hugs.....well theres no PDA in public whatsoever....he would kinda stroke my lower back when no ones there but as soon as he sees someone around...he stopped. but when im at his place or hes at my place....we would do all those things.....but when me, the bf, sis , bro was staying at the hotel for the weekend....he had no problems cuddling and kissing me when we were taking naps while my sis n bro were awake. what is up with him?? my sis asked him about this before and he said that he doesnt really care much about PDAs.....im not asking him to be all lovey dovey and stuff...i just wants us to be able to walk around the mall or any other places hand in hand.....so far....we only held hand while we were walking around SF while waiting for dinner....