I carried concealed when I saw 2016 a couple of weeks ago. I didn't see a sign, but didn't look for one, either.
After the Aurora shooting I've decided to ignore any such signs. The worst that can happen is you get asked to leave. If properly concealed that is not likely to happen. In WA there are few places one cannot carry -- federal buildings, court houses, jails, mental institutions, and any establishment that makes more than 50% of its revenue through the sale and consumption of adult beverages.
It will be interesting to see if anyone sues the theater for their dangerous policy. On the other hand, if I wanted to prohibit antone entering my property from carrying a gun, I think I should have that right. But, people should be smart enough to stay away from any establishment that opts to be a gun-free zone, as such zones are crime magnets.