Thanks IronMax for the idea. I disabled Bad Behavior2, and tried again. Still no love on the Facebook Likes, and even with that disabled, the Facebook Debugger still returns a "Bad Response Code" - 400.
I've looked at the header responses using a few online tools, as well as httpfox, a firefox plugin, and all are giving me 200 responses. What are you using to see the 403 response you posted?
Thanks again! Mike