Two years is quite a long time for a re-seal job.
Get a good step ladder and inspect the seam where the fiberglas rolls over the edge of the roof and goes into the metal trim (J channel) just behind the gutter. Use your thumbs and press inward. You will more than likely see the fiberglas give inward a bit, but it should not seperate if the seal is still good. It can look great and not be stuck.
We had a 2000 Itasca Horizon that was inspected at the factory when we had some work done there. They found about 2 feet of separation. Back then they charged $400 to re-caulk the seams, but told me I could do the job myself. I did. Winne tells us us to inspect the wall/roof seams every six months. I suspect your problem may be the caulk has separated, even if it has not pealed off.
I used a painters tool - sorta like a putty knife, but sharper - and cut all the caulk out. Then cleaned bot surfaces (roof and J channel edge) by wrapping a terry cloth rag around the blade of the tool and running it between the two surfaces several times. (used Windex to clean) When the srufaces were dry, I used caulk I had purchased from the factory store and caulked the entire edge from front to rear on both sides. Force the surfaces apart slightly so the caulk will get between them, not just on the tops. I used a wet finger
to smooth the joint and I was finished. It is not a hard job, just a pain to keep moving the ladder.
Not wanting to do this job again, I bought a roll of Eternabond tape and split it into 2" strips. I marked 2" up on the roof from the bottom of the gutter so I would have a straight line. The let the factory edge of the tape follow the line and the cut edge of the tape follow the bottom of the gutter, lapping over the seam. Rolled all the tape surfaces I could with a wallpaper roller and pressed the areas I could not into place with my fingers. I used the fabric backed Ebond. Now they have plastic backed. The fabric will lay flatter than the plastic, but you have to paint it with UV protectant paint. The Ebond was still in place when the sold the coach last year and the seal job was done 02
You will have a permanent fix and never have to worry about a seam leak as long as you have the coach.