"Mummy" Hagrid

One of the scenes that sticks out most in Harry Potter and the Sorcerer's Stone is the one where Norbert is born.

Visually, it's wonderful, especially for kids. They get to see a dragon hatch from an egg. While this is obviously done through computer animation, for the children it is real kids are so completely entranced with Harry's Wizarding World that they are waiting and praying for their acceptance letter to Hogwarts when they turn 11 and be able to purchase a dragon of their very own.
     Yes, they'll be disappointed when they learn that their letter and/or dragon will never come, but for that brief moment, they believed in something incredible and magical.

As nice as that is, however, there is something else that caught my interest last week when I watched the movie. I guess I didn't catch it before because I was actually watching the movie. This time, I was multitasking and only listened to the dialogue.  And sure enough, I heard it.  . .

Hagrid referred to himself as Norbert's "mummy."

Why would Hagrid, who is clearly a man, claim the title of "mummy," a term usually used exclusively to refer to women?

After all, it's not like he had a mother to love and care for because she ran off. He was much closer to his father, who stayed to raise him. So, wouldn't he naturally be inclined to identify himself as daddy seeing as his own dad was the only parental figure in his life?

No. No he wouldn't.

1. He could refer to himself as "mummy" because he never had one and he didn't want Norbert to live life that way.

2. He saw his dad take over both maternal and paternal roles, so it wouldn't have seemed odd for him to assume both roles.
     That doesn't really explain why he didn't call himself  "daddy" though. 

3. He has natural maternal instincts.

4. He sees himself as the person who gave birth to Norbert by caring for the egg until it hatched; something a mother could do.

Any of these answers (or even more than one of these answers) could be correct, but it does open up a few strong issues revolving around gender roles and gender stereotyping.
      I don't have the time to evaluate this gender reversal from a thorough, scholarly sort of view, but I might later because this is an interesting topic.