On the freeway today I accelerated and noticed a slip under the acceleration. I let off and went back into gear, shifted through all the gears just fine. Once I got off the freeway I noticed when I accelerated a whine that got louder while I accelerated, no noise at idle. It sounded to me to come from the transmission. I have around 155K miles on my 2015 1.4l turbo cruze. Any suggestions where to look, what to check before I take it in to the dealer?