I don't maintain my MANIFEST file manually, but have a MANIFEST.SKIP file and run "make manifest" before the releases. As the MYMETA files are new, they were not matched by any of the rules in the MANFEST.SKIP file.
I added MYMETA.* to the file and re-generated the MANIFEST file using "make manifest". Eric, as I see you do the same with Build.PL with the extra cleverness of cleaning up the old MANIFEST file before. Updating the SKIP file should be enough. Gabor