My wife first noticed this quite a while ago, and tried to point out to the clerk that while technically correct (since ALL cookies are vegetarian), the sign's intent was probably "vegan" cookies. The clerk was adamant that vegetarian was correct, and Child finally gave up.
So I finally decided to go down and take a picture of the sign. Afterwards, while walking back to my lab, I called up the store and asked for a manager. I finally got one, and was able to raise the question of why the sign said "vegetarian" instead of "vegan."
Apparently the lady thought I was some sort of PETA organizer standing poised outside the door with several hundred sign-carrying protesters ready to start marching if the sign wasn't resolved immediately, because she was extremely apologetic, and hastened to assure me she would leave a note for the "guy in charge" to get the sign changed post-haste. That wasn't really my intent, but I knew it would make Child happy, so I cheerfully thanked her and hung up.
Remind me, and I'll check back in a couple weeks to see if they really did fix it.