I think I may have found the problem. During the upgrade, I switched to a new DNS server, and it no longer supports the "alias" datatype that I was using before. I switched it to CNAMES, as almost all the aliases work just as well as CNAMES. I forgot that this technically violates the DNS RFC, so some (really picky) DNS implementations won't work properly. I've corrected this, and in another couple hours or so, all the TTLs should expire. If you continue to have problems, please let me know, as I'd really like to pin this down for good.