Sadly, I can't reproduce this now. I'd rolled back the plugin to version 1.2 (I reverted the change in source control) and carried on working. When I re-updated to 1.3, I didn't get the problem.
Let me know if you want me to test anything or try to reproduce the problem again. I've got a staging site that'll still be on the original 1.2 that I can try upgrading...
Thanks,
Matt