***DO NOT TOW YOUR TRAILER***
Yes, your Tri-Glide is failing and your trailer could separate from your truck. I had two of the three rollers fail from welds that broke. It started with banging every time I stopped or started. If the hitch plate is dipping in the rear you have a dangerous situation.
The Tri-Glide portion of that hitch is no longer in production. NHTSA has been notified of the hitch. Over on the Dutchmen Forum we have a long thread going about this hitch's failure. One hitch owner found that his Tri-Glide portion was only rated for 18,000 pounds and was installed on a 21,000 TrailAir. My warranty replaced the entire hitch with just the upper TrailAir portion and towing has been great since.
Here is a photo of my failed Tri-Glide.