New neighbours have moved into the house behind us. Their bathroom window has clear, not frosted, glass. They only have a net curtain on it. At night, when they have the light on, we can see them very clearly when they use the shower. We're not deliberately looking - their bathroom is in our direct line of vision from our kitchen table. I'm assuming they're unaware that we can see them. Should I let them know, and if so, how should I do it? I've never met them, and I think it would be a very awkward conversation to have with them.