I have an older 34CKTS and EVERY single seal inside and out has come off. They used adhesive and it only lasts so long.
So....I have fiddled with this issue until I got a method that works. I am NOT replacing the seals just because the adhesive got old...and using the same seal with the same adhesive is just asking for same issue.
Now my overall method is not needed for your small section but I can say from trying many different ways that if the seal is subject to a lot of stress then a good adhesive and a sealing the edge where the seal meets the fiberglass worked best. I have tried multiple adhesives and 3M works as does several other contact type adhesives..even GOOP. Note that 3M can be runny...it likes to drip and is messy..just have to see what I mean if you use it...I don't like it for seals because of this...but that's just me.
You have to be sure both surfaces are clean. You can use a couple stainless screws if you like to hold the seal down. I have had to do this in places especially the ends...but in the end the surface contact area of the adhesive is what will hold it down.....the screws have almost no surface area that the head contacts but again..it does hold it down while it sets.
My preferred adhesive is just to use 3m Adhesive tape from HD then do the method below. Second is to use GOOP or similar..it is thick and wont run...then do the below as described.
What helps the most is to (after its dry) use something like a black polyurethane caulk and seal the edge where the seal meets the fiberglass. I tape this off by using masking tape about 1/4 to 3/8" from both edges..meaning on the fiberglass and the seal. This makes a neat line and once I put the caulk down I tool it with a wet finger smooth then remove the tape. Neat clean and this will keep the seal from EVER lifting.
I have done EVERY seal on my 5th wheel this way and you can't tell...and poly is flexible unlike other RV caulk and wont crack. May be a bit more than you want but I would run a bead along the edge where the two meet..this is where it starts to peel..so strengthen this edge as it is the weak point.
I found the Loctite 30 black at HD to work the best. It is one tough grabbing sealant and while you can use an RV specific Poly it is not needed. Plus find it in black...not easy at your local RV place. You will not be able to rip the seal off with a good poly like this.