I believe they were made by Bialetti. It was a Costco bargain pack. I don't recall reading any warnings on the subject, but I may have forgotten.
Because of what most DW detergents will do to unprotected aluminum, I don't put aluminum pans (coated or uncoated) in the DW. The Bialetti skillets are enameled so that's not an issue.
They are just now beginning to lose their super slipperiness so I may have to breakdown and buy another set. I stack my 9-10 skillets in a stack in a cabinet so that may have something to do with it.
"If you want to make an apple pie from scratch, you must first create the universe." -Carl Sagan