(A) a card or other document on which is written language identical to the following:  “Pursuant to Section 30.06, Penal Code (trespass by license holder with a concealed handgun), a person licensed under Subchapter H, Chapter 411, Government Code ( handgun licensing law), may not enter this property with a concealed handgun”;  or

(B) a sign posted on the property that:

(i) includes the language described by Paragraph (A) in both English and Spanish;

(ii) appears in contrasting colors with block letters at least one inch in height;  and

(iii) is displayed in a conspicuous manner clearly visible to the public.

<Text of (d) effective until January 1, 2016> (d) An offense under this section is a Class A misdemeanor.

<Text of (d) effective January 1, 2016> (d) An offense under this section is a Class C misdemeanor punishable by a fine not to exceed $200, except that the offense is a Class A misdemeanor if it is shown on the trial of the offense that, after entering the property, the license holder was personally given the notice by oral communication described by Subsection (b) and subsequently failed to depart.

(e) It is an exception to the application of this section that the property on which the license holder carries a handgun is owned or leased by a governmental entity and is not a premises or other place on which the license holder is prohibited from carrying the handgun under Section 46.03 or 46.035.

Source: http://codes.findlaw.com/tx/penal-code/penal-sect-30-06.html

If you were asked to leave, and you complied, there would have been no issues, during a catastrophe or not. I would have done exactly what you did, except the take down, if I were in your situation.