Depends. The whole point of concealed weapons is that other people aren't aware when you're packing a piece. 
However, if I see that sign, and I'm carrying (very unlikely), I don't go in.
Here's what the law says:
"A person who wilfully violates a provision of this subsection is guilty of a misdemeanor and, upon conviction, must be fined not less than one thousand dollars or imprisoned not more than one year, or both, at the discretion of the court and have his permit revoked for five years."
