Unless you have a lot of blues around that blue you see is most likely yeast blooming. Not that it's that important what it is but just for curiosity. I had the same looking growth on a cheddar I have but in doing more reading on the forum I'm fairly sure it was yeast not mold.
It's almost certainly mold (penecillium roqueforti). I'm not a molecular biologist, but I do ferment a few things and I've never heard of any blue yeast.
Not that that's bad, but on many cheeses you'll want to wipe it down with vinegar/salt to remove. I keep blues and other cheeses in my cave, and if there's any transfer I wipe down. I keep cheesecloth over my blues to try to inhibit blue travelers.