Wow, what a story. It almost sounds like a fiction.

I do think that if you are doing nothing else illegal, and just mining, then the reason why all this happened was probably because of your electricity usage, especially when you are living in an apartment. Using so much electricity is simply not normal.

It could be possible that the police is working in conjunction with the power companies to catch weed growers, i don't know. It's a really wild guess. I have never mined with a lot of equipment consuming tons of energy, nor have i ever grown pot indoors. So i don't know man. Just try to not make yourself look too suspicious and you'd be alright.