Well, that's nice you got such a prompt reply.
Interesting that they stated there were no changes to policy that they were aware of, but I wonder if there was a policy to begin with?
She didn't state you were in violation of any policy by OCing into their stores, but it would be an assumption that there was no policy.
Since you've started a conversation (of sorts), you should maybeEmail her back and ask:
You stated there were no changes to policy. Is there any current policy concerning customers carrying firearms? If so, what is it?