I accidentally let my GPG subkey expire 2 days ago. If you were trying to send me encrypted mail, you couldn't. I'm working on fixing this now.
Update: The expiry on my key ID 608c0112 (and subkey) has been updated, and uploaded to keyserver.ubuntu.com and subkeys.pgp.net. If you have any trouble encrypting mail to me, it should be enough to refresh your keys. Sorry for any inconvenience!