mine did that, when it was set to cruise control for 60 mph, the car slowed to a stop to let another car turn right, i pressed the button to make it go and it started to pull as it got about a third the way up the hill 30-35mph, it just would not pull anymore, I had cars behind me, so had to stick my foot on the accelerator pedal, just to get a move on, but once at the top i let my foot off the pedal and it cruised happily at 60 from there...
Spoke to my dealer about it, and they said they knew nothing about this issue, i stated I had seen it mentioned a number of times on various forums, no reply from there... I will email again today to say that there is an update coming for this problem !
Any idea when it might be ?