Untrue. A non-stick pan (teflon, calphalon) is actually LESS porous than it's traditional counterparts. Think about what the bottom of a cast-iron skillet or aluminum saute pan looks like and compare that to the smooth surface of a non-stick pan. All metals are porous to some degree, so if you're that worried about cooking on a contaminated surface, do the Kosher thing and have a set of cookware set aside exclusively for gluten-free cooking. Personally though, I'd be more concerned about porous cutting boards, countertops and utensils (especially wooden utensils) than a properly cleaned pan. Just make sure to clean your cooking tools and surfaces with hot soapy water and you'll be just fine. Hope this helped.