Yes, it’s Roy Walton’s classic trick where one card folded inside of another magically turns inside out.
Oh, but was it magic, or did you use the power of your mind? (Seriously, if metal bending can be considered mentalism, then cardboard bending for sure could be mentalism.)
If you don’t do Card Warp, give the PDF document a look anyway — it may spark some ideas for you to reframe some of the magic you do as mentalism.