I don't see that OP's set or brand name listed at Costco's site.
Costco.com doesn't necessarily carry the same stuff as the stores. In fact, different stores have different inventories. I have often heard others talk about a specific item and not found it at my Costco.
"If you want to make an apple pie from scratch, you must first create the universe." -Carl Sagan
Interesting. You're cooking with raw aluminum. Do you notice any off flavors or colors with acidic ingredients?
My MIL used to use metal utensils with her non-stick pans. Lots of the non-stick was scratched off but she kept using it. We asked her boys if they thought she was cooking with lots of pepper. (black specks throughout the food.)