What's that about?

Mistress Wife says:
hello u slave boy
Mistress Wife says:
wanted to quickly say that I am sorry I've been grouchy lately and instead of being grouchy with you when things are not right. I'll just have to train you better
Mistress Wife says:
I'll crack my whip and be a tougher mistress
Sub Hubby says:
Hmmm
Mistress Wife says:
what do you mean hmmmmm?
Sub Hubby says:
Well, I would say Thank You Mistress, but why say that to someone who is promising to thrash you?
Mistress Wife says:
thank me as it will make you a better slave so less thrashing in future
Mistress Wife says:
gotta run anyway, so talk later xx
Sub Hubby says:
Yes Mistress. Enjoy. Bye. xx