I walk past Bucks with some regularity and have seen their sign up for years now. A day or two I walked by and noticed it was missing.

there were a lot of other signs up so it didn't appear to be a case of 'take down and wash the windows, put back up tomorrow' or something similar

Hmmm. I had a conversation with an owner five or six years ago. He made it clear he was happy to lose permit holders' business.

Hmmm again: In these tight financial times, maybe a "Can you afford to lose 57,000 customers?" pamphlet would be a good idea...

Open carry the next time you're through there. See if they give you the boot, even with no sign.
I'm of the school where even if the venue isn't posted, but I know the owner is anti-constitutional rights, I'll still not patronize his business.

Let him show his true colors!

When you are going out of business, you can't be too picky. Now, can ya?