This is true: he is not yet aware how little the man called Thenardier deserves the sense of obligation Marius feels towards him, and though Gavroche attempted to warn him, he will not be easily persuaded of it.

At Eponine's words, Marius blushes and lowers his eyes. "I little deserve such esteem. I regret a great deal about-- about that night, not least that I could not do more for you, could not help."