[AW128i]

On the highway (typically), accelerating in 5th gear, transmission upshifts to 6th with a noticeable thunk. Happens every time if the driveline is under a decent load while shifting into 6th. Normal driving and light acceleration yields smooth upshifts into 6th. Got the car with a hair under 24,000 miles on it last November and now I'm about to hit 50,000 miles so want to get it in for warranty if this isn't normal.