I'm so tempted to say "what a bummer", but I've lost a few things from my bikes over the years. I guess you'll be able find a replacement, even if it means buying a whole new seat if you have to.
It reminds me of a time while sitting on a wall in town having a cigarette when this BMW R100 comes along. The wall was on the apex of a 90 degree bend as and the bike came around the bend, the lid on one of his side panniers popped open (hinged downwards) and centrifugal force deposited its contents all over the pavement in front of me. I jumped up into road behind him shouting and trying to attract his attention. To no avail. He just rode on and disappreared into town. I took the contents (usual touring accessories) to the local police station in the hope that he might recover them.
I've lost two garage remote control handsets whilst riding. Anyway, at least you know the weak spot of this mod if you decide to redo it.