Not cheating, the reference (a tree carving IIRC) would be in the tree before the events of the first game of the series, so before guybrush would have met Elaine. It’s understandable that she would have lovers before guybrush, but the implication that one could have been the big bad LeChuck, makes guybrush fume, even if it’s just an initial.

He also notices she got rid of their picture and a few other things I thought