sounds just like the problem I have been having, I actually have an appt scheduled for later this week to look at it.
My problem occurs right around 40 mph, when I am hard on the gas, I notice nothing, but only when I real soft on the gas, that's when I notice it. Very annyoing!! I was thinking it might CV joints as well, but my understanding is that a rear wheel drive car doesn't have CV joints.
In any case, once I take my car in, I will post what the problem was.