First there's the fantastically named Lía Limón, who doesn't agree with her party's posture on same-sex marriage.
Second, with a good bit more publicity, there's Manuel Clouthier, who criticized Calderón's security strategy for its lack of commitment to Sinaloa, criticized the subsequent criticism of his comments, and is now listening to calls for his resignation from the party. More on that here from Richard.
A certain amount of sniping and disunion is only natural as the presidential campaign approaches, but a lot of what's been pulling the PAN apart in recent months isn't the inevitable electoral jockeying. That's got to be a bit worrying for PAN supporters.