Im a t4r newbie and totally lost in this senario... About to go into the dealer and could use some indication of WTF happened to my truck before I lend it to my parents for a week.

I was driving around Phildelphia this past weekened and about 25 minutes into my trip on a minor highway. We were going between 40-50mph as I started to descend down a half mile hill I let off the gas to coast. Soon after my truck began rev'ing the engine very loudly (or at least it sounded that way). Using the brakes to slow to truck did not calm the engine to a "normal" sound. It seemed (sounded like) i was gaining speed (from gravity i think) and observed I was not noticeably gaining speed on the dash nor did my rpm's seem high. I have never heard this loud rev'ing sound before and began to pull over while lightly applying the brake. The sound continued as I reached the flat road at the bottom of the hill and ran out of shoulder to pull off onto. The truck didnt seem to accelerate normal for a few moments but I carried on up the road about half a mile and pulled over at my destination. Upon restarting my truck to drive home things seemed normal. (normal as much as it can be considering I still dispute that the vibrations and hard shifting/stuttering are not normal) Why the loud rev'ing occurred I have no idea, please help!

Is this a normal function of the truck? I had previously asked about the resistance while coasting to a stop... could this be a similar function of the truck? If so, does anyone else find it invasive, or do I need to be schooled of why that happens in the first place? Also could the hard shifting/stuttering and this rev'ing thing be symptoms of some other issue/concern?

I'm going to be lending my truck to my parents in a few weeks while im away and dont want to worry about potential safety issues. Thanks in advance for your help.