I was trying to get up to highway speed and stomped on the gas on the onramp and the tranny seemed to protest by making a stuttering shudder. In "normal" driving the tranny is as smooth as ever. I also noticed this in a loaner G. Has anyone else felt anything like this and if so what is going on?

 

Don't quite understand... does it shift through the gears (up/down perhaps) very fast?