I know I'm late to answer this, but I figured I'd post for future reference. If you're making a dip (or anything) from scratch it's pretty easy to avoid gluten. The bigger concern is cross contamination. Gluten is a very sticky substance (and often used in glue!) and can seep into porous items like ceramics, stoneware, cast iron, teflon, wood, and plastic. When I prepare food away from home I try to stick with stainless steel and glass.
When using prepackaged items a good cheat is to use generic brand items. Most generic brands (and some big name labels) will list when an item contains wheat. Barley and rye aren't usually listed, but they're much easier to find in an ingredients list.