I think she knows who and what Harry is, but he doesn't know who he is, so she is establishing who is boss.
The "Queen" outranks the "Knight," and dominance-games seem endemic to Winter.
I don't think Mab can help herself.
OTOH, I think Mab has largely lost touch with her humanity. Harry keeps surprising her, and she regularly underestimates (is surprised by) those who still have theirs, such as Lady Winter Molly.