Check the ingredients on the yogurt. Last time I looked at the actual ingredients, it said that it was on shared equipment with wheat. I called the corporate office and they said they didn't test it so I'm not sure how they can say it's GF. It may be no gluten ingredients but that doesn't always mean GF.
You have to know what has gluten and what doesn't before you order - don't expect a minimum wage ever changing staff to go out of their way to research gluten sensitivity for you. Ask about the individual ingredients for your concoction. I'm celiac and I had the peanut butter banana smoothie, 4 safe ingredients, with no issues.
Pinkberry is a great treat in terminal D of the Charlotte Douglas airport! They have a GF list you can read from (I looked on the internet) and the Greek yogurt is GF but the frozen yogurt is not... Lots of the toppings are GF.