[joshiee]

to me it's plainly wrong for a comma. but I also don't like to color outside the box. perhaps an ellipses would've been ok.

[bigwavedave]

Don't worry, your instincts are correct. The only time a comma should follow a conjunction is if there is an interrupting phrase that breaks up the sentence. Example: "He's a nice guy but, to be honest, he smells like a hippopotamus."

[gabereiser]

I learn so much from grammar folks. :D