I have read a bunch of posts about how people hate the 1st-4th shift. After about 2-3 weeks of having my new rt I hadn't experienced it yet. Then one day it happened, it kind of made me nervous cause I forgot it could happen. Anyway I have noticed it only happens when I slowly, slowly accelerate. Otherwise it never happens which to me is no big deal. Is this the "Norm", or does happen at other times also?