Does bending drywall weaken it?

I bought 1/2" x 4' x 16' to install on a ceiling with 16" centers. When the lumber yard loaded it they used a fork lift in the center of the 4 sheets to lift it onto my trailer. As they lifted it the panels flexed so much that it almost bent in half. I couldn't believe that it didn't break.

Now I'm concerned that flexing it that much could weaken it and that it might not be rigid enough to use on the ceiling. Would bending the sheets that much weaken it?"