Girl's face going numb after orgasm

[Apollo]

So recently during sex after my girl comes she says her face goes numb (maybe it goes numb during orgasm but she can't feel it afterward), and she was wondering if it was normal. I thought I would check with you guys to see if anyone else has been with girls who had similar experiences. It usually happens when I go down on her but it's happened when she's come while I'm doing her in the missionary position.

I figure it's just the blood leaving her face, but it still doesn't seem normal.