i had the same thing at about 22,000 miles took it to the dealer they put a new clutch in it and i havent looked back no problems since, i now have 37,000 on it.
does it stop after you have been running for a while? cuz mine only did it in the morning after the car had a night to cool all the way down. after the first few lights i went away tho. this was last summer too.
good luck, my advise have a tech. drive it and feel it behind the wheel.