Would would

In "Last Vegas", Michael Douglas invites Mary Steenburgen to a party:

Well, I would really love it if you'd stop by.

Why would he say that?

I know there are all kinds of accepted mistakes like:

- there's 3 glasses on the table

- I say "x" and he say "y"

- he told me he loves you

which already creep me out... but this? Sheesh!

And, like Carrie, I can't help but wonder: are there no rules anymore?