My understanding is that Gina is simply doing this to ensure that she has done all she can to not have under age ladies on her site. With all of the recent focus on underage girls in the business (recent news story "Selling The Girl Next Door", etc), I believe she is just being cautious. This in turn will also protect the guys more and help them avoid seeing someone who is underage (at least via P411).
Dreams I completely understand your concerns, you might want to contact Gina and clarify what she needs from you. However, in the end only do what you are comfortable with!!!