I really can't tell for sure, but it looks as if what's on your pan is food residue. I used to represent Calphalon in retail stores, and we were told to recommend the dark green Scotch-brite scrubbers on the anodized surfaces. I use a stainless steel mesh scrubber on mine when necessary with liquid dish detergent. The Calphalon people also said that even if the gray surface wears away, it's still anodized aluminum.

Thanks for the information. I have actually scrubbed both pans with the green Scotch-brite, in addition to Barkeeper's Friend and various other options. Appreciate the info.

I have returned 3-4 different pieces when non-stick just wasn't all that non-stick any more. I received brand new replacements... only had to pay to have pieces shipped to C, didn't need any receipts.

Just Me, I, too, suspect that the discoloration is food residue. Try a Brillo pad and see if that will clean them up. If not, then try sandpaper (100 or 150 grit to start with, then finer grits if you wish.) I have an older heavy anodized saute pan where all the dark grey anodized looking coating is worn away and looks like regular old aluminum. One of my favorite pots.