Had the same issue. Used a Zodiac Dealer to repair it. What they did was use the Zodiac PVC glue to reattach the the floor area while it was inflated fully. They then glued an additional patch over the reattached area for reinforcement. Nice clean patch on both port and starboard to match. Could pass for factory.
They said the reason the nearly new looking Zodiac separated at that seam/joint was that the boat was probably stored deflated for a long period. Maybe in a garage where the temps were high. I know that the previous owner used it only twice and stored for years, deflated, before I bought it.
I use it as a dink, so it's inflated 24/7 on the stern. No problems the last 6 years.
If you are handy and a little meticulous, you could probably do a nice DIY job on it.
I, on the other hand, was cursed at birth with little innate talent and a pronounced lazy streak.
1996 Zodiac Series 134 (11'2") PVC, wood floors. Pushed with a 15hp Honorable Tohatsu, and it's not a moorage queen. Should be good for 5 or 6 more seasons.
Hope this helps.