I actually saw some video recently about a shamwow from like 7 years ago that just recently blew up. All of the comments were from the last 3 days and said how the video was everywhere on the homepage for people until they finally clicked it. I'd guess that the same thing that happened to this video, is the same thing that happened to yours. It likely just had a huge influx of showing up on peoples homepage suggested and people clicked through. YouTube probably released a new homepage suggested videos algo or is tweaking their old one.
Complete guess, but I doubt anyone else will be able to tell you definitively what happened. Unfortunately theres also no way that I know of or have read to further have your video show up on the homepage, so its kind of it happens and you're lucky or it doesn't.