I posted this elsewhere but I wasn't sure if it was in the right forum, but here goes...
I bought a brand new 2012 F150 3.7 XL reg. cab this past April. Everything was great until about 4 weeks ago. I began to notice a slight, but noticeable vibration or shutter upon take off. It wasn't there before, at least I didn't notice it, which I probably would have because I'm nitpicky about my truck. It only happened from a dead stop, but it doesn't matter how hard the takeoff is. It lasts about 1 second. I tried it in 3rd gear and didn't seem to notice it. Does anyone have any idea why this is happening to a 5 month old truck?

Also, the truck had been taken care of. Never really abused it in anyway.
However, the only 2 things I could think of that might be linked to this would be 1) a few weeks ago, someone backed into my truck, but it just hit the ball hitch and caused no visual damage. It was really more of a love tap anyway.
2) we recently purchased a 17 foot inboard Welcraft boat. This dry weight of the boat and trailer is roughly 3000 lbs. We have been using my truck to take the boat the the ramp, which is about 30 miles away. But the truck really doesnt seem to strain itself while towing, except maybe when stopping.


Also it does the same thing while stopping. It's like it takes the bed a second to catch up with the cab. Honestly, it almost seems as if it is getting worse. Of course the truck is still under warranty.
Is this a probelm or is it possibly normal?What would you guys advise for me to do? Thanks in advance.

 

And also, if I stop ultra slowly, to avoid the vibration, then it will not vibrate on take-off...this has me concerned. There is obviously something loose. Somewhere..

 

My truck has done this since new, very slight though. I now have 23,000 miles and am not worried about it at all.