It sounds like something is slightly warped, so the potential problem (if any) would be a light leak. My hunch is that if you can shove the corner in place enough to lock it down you are probably OK, but I would try to develop a sheet exposed in portrait orientation relatively soon, rather than shoot a bunch of sheets and discover that there is a leak. I guess to be safe I would expose and develop at least one sheet in each orientation just to be sure.