How scarey! Is there any chance the cop 'thought' you could see him? I mean that you could see his uniform? A bit of lighting in your yard?
Not to scare you more, but after living next to a drug house for years, (they're gone, thank God)I've come to the conclusion, druggies tend to think, YOU are a druggie too, simply because you live next door. Hopefully, they'll not be your neighbors for long.