This is what I would do at that time

I would give a smile or laugh out of embarassment, and say thing like "sorry about my language, you know what I mean" or joking "I didn't mean you know nothing, I mean you know nothing" or making fun of myself for such a stupid comment. Something that will make it lighter and showing I was just joking or making a stupid language mistake.

But since you didn't say anything at that time, don't make it too big a deal. It may never be a big deal unless you make it. Treat her nice and you will become friends.

That's another advantage of being loose in the office, then you will mostly be forgiven since you comment on almost everything loosely.