I'm sure you'll get a response or two from LEO in this thread (and I'd default to their judgement on this one), but if your gut was really screaming at you in that environment, you could call in a wellness check via the non-emergency line.

Tell the non-emergency operator you attempted to get the home owners attention, couldn't, and that you're worried something might be amiss.

I don’t want to be that guy, but I’d hate to think someone shady could be going on there.

Nah, this is the sort of nosiness that I can get behind. No one is getting hurt, and you're not being a dick. And you never know, maybe the owner was in the midst of a medical emergency and is incapacitated.

It'll take 15-30 minutes out of the responding officer's time, depending on how far out it is. No biggie.