The neighbors were probably just having some sort of party where the odors might have presented embarrassment if they had opened the door.
The bike probably needed a good servicing anyway, so a period of outdoor exposure or even immersion would do it no harm.
That said, when my own very cheap (un-sealed hubs) mountainbike was subjected to a heavy downpour while being driven back from Tahoe in a horizontal position in the bed of a truck, I rebuilt the hubs the very next day. As I'd expected, the hubs needed the service anyway as a lot of dust had settled in there.
Maybe at some point you'll run into the neighbor outside and can make him/her a tidy offer on the steel Trek. Look at this as an opportunity!
