No, really, he said so himself:

I want to thank my friend, Senator Bill Frist, for joining us today. (Applause.) You’re doing a heck of a job. You cut your teeth here, right? That’s where you started practicing? That’s good. He married a Texas girl, I want you to know. (Laughter.) Karyn is with us. A West Texas girl, just like me. [WhiteHouse.gov by way of Wonkette]

So much makes sense now…