[Grammar] Is it correct to say, "I didn't know that you live in London"?

[Mike MC]

Consider the following conversation:

Joe: I live in London.
Ben: Really? I didn't know that you live in London.

Is it correct? Or should we follow a strict sequence of tenses and say, "I didn't know that you lived in London"?

 

[GoesStation]

I think most native speakers would back-shift the verb and say lived, but they're both possible.