By definition, the track should be in the iTunes Match library (which contains everything bought on the same AppleID through the store). But it isn't for the Match library ON THAT DEVICE until you take action to make it show up ... via the iTunes store.
You cannot fucking tell me that isn't a bug. That is a bug. And no, there's no mystery refresh occurring once every 24 hours, because I've had tracks fail to show up for longer than that. For all I know, there are permanently inaccessible tracks.
ETA: For all instances of "iTunes Match" probably replace with "iCloud Library".
ETA: Upon further reflection, I suspect that I know why this happened. You can delete stuff from MyMusic on a given device without it going away from the iCloud Library -- as in, it doesn't show up in the library listing any more. So while _I_ think that all devices should have windows that show the _same_ library, in fact each device has a window that shows a filtered version of the library.
Bad Hack, Apple. Very bad hack.