Jonathan, this is fair. I let you use the spare key to the house as I was coming back from out of town. Never have I had someone borrow the key and then keep it with them overnight, thereby locking me out. I apologize, going forward I am installing a digital lock on the front door so that this won't happen again.
This was one of my closest friends in the Morristown area for the past three years and we had come back to talk while he waited for his ride before his cross country road trip for the next few months.
I'd like to offer to refund you those two nights, please follow up with me with a request. Good luck on your continued travels and thank you for the advice about where to visit in Colombia and South America!