i think i have the same creek, and yes its the hand brake as far as i can tell. if jiggle about in my seat before i get out i dont get the noise, but if i get out quickly just after putting the hand brake on it makes a small creek sound, i just assumed it was due to my weight coming out of the car, not that im heavy, but its still a difference.
however my hand brake does need an adjustment i think as i have to make sure its engaged quite high, other wise it doesnt bite, but to be honest i leave it in gear just in case.