First, I need to see a pic. I fell in love with the breed 25+ yrs ago when WHV were largely unheard of, and since then have simply fallen in love with them, their appearance is so consistent with their true personalities.
Anyways, socialization is a work in progress, but instinct is baked in at birth. We could say that what makes them "Domesticated" (or perhaps, "Trained") is the emphasis on "Socialization", which counters instinct. The more any dog is socialized to it's human environment (including the environment with other dogs), the less "Instinctual" their responses are, which is most often a good thing. As a pup, it's balanced much more towards "Instinct", more out of survival. So, the behaviors you describe when she rolls over are pure instinct. The goal is to help her manage that and learn more thru socialization. When she rolls over for humans, I'd bend down to her level, and gently give her the "OK!" signal so she hears from her trusted person that there's nothing to fear.
Of course, when she does this at home and is just hangin' out and being relaxed, you can indulge the urge to rub or smooch..one of the advantages of being that trusted person!