I had a similar problem with a PVC boat that I had cleaned with Wesley's Bleche White, After a couple of years of this cleaning the fabric started to get gummy, sticky and 2 years or so later the seams started coming apart, I had always assumed it was the harsh and inappropriate cleaner that caused my problem, maybe it was the other PVC issues mentioned above. FYI, I bought the boat new in 2000 so it was probably made in 1999. It gave up the ghost in 2010. The fabric started getting sticky in 2008 or so.
Don't Wanna Die Askin' for Another Chance