Retina Macbook Pro USB 3.0 not working

I have had trouble with the left USB 3.0 port. It becomes finicky and drops out and loses connection. I am not the only one that has found this with the 2012 Retina Mackbook Pro. Three of my photographer freinds have found this also as they have the exact same machine as I do...? All the machines mentioned are Apple Refurbs. Anybody else have this problem?