Its a harmless Log message, they are a bit annoying for sure but not an error.
I think this one has something to do with Templates and GC updates made in recent Unity patches, I was seeing it a lot too in projects that use a lot of Templates and/or RunFSMs but I don't personally remember seeing it before 4.6... Can't remember if Alex did anything in the Beta to tidy this up or not but I haven't noticed them as much (or at all, now that i think about it..) in the latest patch.