A little clarity is needed

While walking home from school this rainy afternoon, I saw the following sign in a liquor store window:

IMPORTANT! If you appear to be under 25 years of age before entering the store you must present valid picture identification.

Now, I'm a bit of a punctuation freak, so this sign practically SCREAMED at me. Does that mean if you appear to be under twenty-five before entering the store, you must present your I.D. just as you enter, so in case you put on the fake beard and dye your hair grey, they know about you up front? Or does that mean you have to stand on the street and hold your picture I.D. up to the window before they let you inside? In either case, I don't think I'll be buying anything from that store any time soon.