(g)  A dealer of firearms shall post in a conspicuous position on the premises where the dealer conducts business a sign that contains the following warning in block letters not less than one inch in height:
"IT IS UNLAWFUL TO STORE, TRANSPORT, OR ABANDON AN UNSECURED FIREARM IN A PLACE WHERE CHILDREN ARE LIKELY TO BE AND CAN OBTAIN ACCESS TO THE FIREARM."

I;m not sure I've seen anything but the federal sign at a gun store.

I've never seen it before.

Yes I post it.

Part of the youth handgun safety act? I see that posted all over, never really read it.
Its safety, its not just for youth.

Nope.
What the OP posted is a Texas requirement, not the same as what ATF requires.