Anything's possible, but I don't think Trek ever used steel dropouts/fork ends in their carbon or aluminum frames. The pictured dropouts are thicker than steel would be, or so it looks to me, and the finish is the uniform dullness of aluminum. FBinNY and several other experienced posters seem to have taken for granted that the dropouts are aluminum, as did I. If the OP wonders, a magnet test would answer the question immediately.