Q: "Do you have any juice?"
A: "Yes, there's some in the fridge."

Sounds perfectly fine to me, but:

Q: "Do you have any towels?"
A: "Yes, there's some in the closet."

Does not.

I asked for towels - plural - so wouldn't "Yes, there're some in the closet," in which there are is turned into a contraction be the correct way to say it?

Spellcheck, however, doesn't like "there're", and I think I'm the only person I've ever heard use the word "there're". Even folks who I know say "there are" shorten it to "there's" when possible.

Am I saying it wrong, or are both forms acceptable?