The signs by the frozen yogurt dispensers indicate which flavors are gluten free. Another sign warns about possible cross contamination when one of the flavors in a machine contains gluten. I stay away from the toppings because there is also the possiblity of cross contamination, both by the staff and customers who might use the same spoon for different toppings. I was careful and had no digestive issues.
With the exception of our yogurt flavors which use ingredients that would explicitly contain gluten, such as the double cookies and cream, our yogurt flavors do not contain gluten. However, all of our flavors are processed in a facility that also processes products which do contain gluten.