Is it normal that i like when my girlfriends ass cheeks are cold?

i really like when my girlfriend has a cold bum from being out in the winter weather or what not.she comes in from outside and lets me feel her bum now that she knows i like this :) and somtimes we have sex right away and i just love the feeling of her cold bum cheeks against me while im inside her warm pussy . i dont know if its the contrast in temperature or what but is this normal?