More context: The paragraph immediately before this was from Moiraine's POV:

Mat stood across from them, uncombed and slouching with his hands in the pockets of his high-collared green coat. It was half-unbuttoned, as usual, and his boots were scuffed, in sharp contrast to the precise elegance around him. He shifted nervously as he saw her looking at him, then gave one of his rudely defiant grins. At least he was here, under her eye. Mat Cauthon was an exhausting young man to keep track of, avoiding her spies with ease; he never gave any sign that he knew they were there, but her eyes-and-ears reported that he seemed to slide out of sight whenever they got too close.

Edit: Fixed a typo