Well, in my experience, while I've been asked to leave a couple places, I've also returned to those places later while carrying and have so far had no more than one issue per place. Honestly I think it's a fluke occurance that just happens once in a while. For the majority of the six months that I've OCed, I've had no problems at all. Tons of questions, but no "GTFO" or MWAG calls. There've been a few uncomfortable situations, but it's rare.
Then again, it depends on the area and the community. My area is pretty rural. But I have carried in Louisville, Lexington, and E-town, and so far have had no problems in any of the places I've been (other than the Fayette mall having a very aggrivating sign that bans all weapons of any kind). The same goes for Campbellesville and Bardstown.
Honestly, if you go back, the worst they can do is ask you to leave again. And even if you said no, there is nothing they can do. There is no sign posted. You are not breaking company policy-- they are. You are not breaking any laws, or even any rules of Walmar. The worst you're doing is making some silly sheep duck behind their shopping carts because they're afraid of your rights, and maybe annoying a manager or two. Sure, they can call LE, but the cops will probably just tell them to stuff it, or possibly just ask you to compromise and go somewhere else (to that, I wouldn't suggest saying no!). And even if you do get bonehead LEOs, nothing would stand in court.
The worst you'd be in for is a headache, which doesn't seem likely from where I'm sitting. However, to my discredit, I have no idea where your area is or how your community sits with the 2A.
But hey, on my bad days I'm a little headstrong. What can I say? I'm passionate and steadfast when it comes to my rights.
In other news, IANAL. My knowledge of laws and various corporate policies are just from my experience (albeit rather limited), in addition to information relayed and imparted by these forums (not so limited). It's all stuff I've learned or gleaned-- not legal advice. /end_disclaimer