Strange case of griefing(?)

Hi there, a player called Miniheadshot seems to have been griefed, or at least, that's what we think could have happened. Well his pig spawner went missing but logblock's latest log is not telling that it was ever broken.

Screens say more than 1000 words right? So here is one:

Yea, I rolled back that guy a while back, and it did not rollback the spawner. So I placed a new one.

"did a unspecified action" usually means they broke it.

Indeed Yarwood, However after that happened, it was replaced (The line above it), And there is no further entry about what happened.

The only idea I have is that it was placed just before a minor rollback. The only reason this comes to mind is because I know logfiles are stored separately, and would not reflect things that "Happened in another timeline" if that makes sense? I have seen a couple of rollbacks of one or two minutes when the server has died before, but I don't know if there were any around that time, and don't have the ability to check that.

It would mean that the spawner was removed by a rollback or with World Edit, or something that is not logged, I would think...

I believe removing a mob spawner in general results with, (insert name here) did an unspecified action, as I have had to deal with this before.