Yes you can boost an old post. But I don't know for how long. Looks like I can't boost really old posts but I can boost posts I made last week. 

That's what happened. One thing: Is it possible to retroactively boost a post that has already been made? 

siggy47

I didn’t notice anything out of the ordinary. Was a bit of a slow day in sports. Last time I had something like this someone had 10k boosted in the territory.

What's Up With Territory Awards?

I didn’t notice anything out of the ordinary. Was a bit of a slow day in sports. Last time I had something like this someone had 10k boosted in the territory. 