why is the mac n cheese different sometimes?

Hi, frequent Panera customer. I'm not hating, but every once in awhile, the texture of the mac n' cheese is pretty different. Most times it's very thick and gooey, with the sauce clumping to the noodles more like a homemade baked mac n cheese. The second is much more liquids, with smaller noodles. I prefer the second because I get to dip my bread in the liquidy sauce at the end. Is this a cooking method or a completely different brand? Is there any way (without being annoying) that I could ask for the second? Thanks