Guessing those tricks will work, or any number of inflatable/vinyl repair kits. Might be hard to fix if it's on the edge though.
I'm sure you didn't do this, but It helps to avoid over-inflating these seats, I squish at least 25% of the air out before closing the valve. They feel more comfortable this way too.
I LOVE my Hobie comfort seat - but it failed pretty quickly. It simply tore loose from the velcro section. Near the area you are describing. Anyone else experience this?
There is only a very thin strip of vinyl holding the cushion to the velcro. Once a crack develops at the edge, it will soon tear all the way, like a perforated sheet of paper.
Couldn't figure out a way to repair it so I just cram the cushion under my Okole and hope it doesn't float away while I am out riding the Hakas. Bound to happen someday- and it will be like throwing two $20 overboard.