First off, there is NO law in this state requiring a business to post "no guns" signs. IF it's private property, they can ask you to leave for any reason at all, including because they don't like your gun. If you refuse, you can be tresspassed by police, but it's not a gun violation. There used to be a sticky with a good pamphlet, but looks like it got lost with the forum switch. Someone will chime in shortly with where to find it. You may want to check with Trader Joes regional management/customer service. The company may or may not have a policy prohibiting firearms, or the manager might be acting on his own.