Fortunately Megatron has no idea what blushing is either. He has never seen an organic life form blush before, ever. Pretty much nobody in the universe blushes when confronted with Megatron. Perhaps this is some kind of fear response? Hmm.

"Oh, but I insist." He grins. There are no fangs involved at all. It is sort of uncanny. "I recognise a fan when I see one."