First welcome to OCDO (OpenCarryDotOrg).
Second, the LEO may not have actually been lying to you. If private property owners do not prefer to have OC on their property, in most cases they can ask you to leave. The LEO may have been giving you opinions on your type of holster and being pushy, but the law precede him. Posted or not if the manager asks you to leave you must comply and then can take it up with corporate, later.
Third, it's a good idea to get an Olympus-type voice recorder, and where legal (one and two party states, other situations vary) run it whenever you are OC in public (and sometimes it's a good idea to have when on your property, also). Get the type with a USB port and long play times and get into a habit of carrying it on you, running if you have a firearm with you.