The patch was indeed moved by all the jostling. It was otherwise intact.
Replaced and augmented, the new patch should hold until the weekend. But now I have other chores and must rest before I work tonight.
I'm thinking of cutting up a 22 oz (.65 l) beer can with tin snips and fastening it around the patch with metal strappings. That should outlast the Geo itself.
Other suggestions? Include autoparts store, where applicable, please.