We've received mail from our old neighborhood(which is nowhere near where we live now)before, as well as mail from neighbors either up or down the street or one street up or down from us but the same address number before.
I've also had the 'delivered' notification come up on packages in times past, then received them the next day. It happens.
However, since it's been marked as delivered since the 3rd of this month, I would say that unfortunately you guys are SOL at this point.
I know that whenever I send a package out anymore, I'm tracking it from the moment it leaves my hands till when it's delivered and then I tend to PM the other person a bunch to make sure they got it.
I had a scare recently when I sent out two games to two different areas(TN and MA) and the package going to TN got there before the one I sent to MA, which proceeded to play ring around the

in' rosie in the Boston, MA post office getting sorted and scanned FOUR TIMES.
I live in PA, so the package going to MA should've logically taken a shorter time period to get there than the one going to TN.
Then again, this is the

in' post office we're talking about here. The same post office that bounced a guide package from here all the way down to either North or South Carolina, when it was only being delivered to an address in VA.