I think Link lost his ToC in MM as soon as he fell down that shaft into the Termina dimension. My evidence is from tWW when the Red Lion boat tells Link about having to go find the shards of the ToC because he mentions that the original Hero of Time (Link from OoT/MM) left Hyrule on another quest (MM) after defeating Ganon, separating him from the things that made him what he was, and he said that the ToC shattered as a result of him doing that.

I think, now that you mention this, that the triangle thing you saw may have been Nintendo's way of hinting that he didn't have his ToC in MM.