About a week ago I started using a magnetic case with my Nexus 7 (Slim Fit Leather Case by SupCase-http://www.amazon.com/Google-Nexus-Tablet-Leather-Supcase/dp/B008HDLI9Y/) and shortly thereafter, the tablet would randomly go into sleep mode when I had the front cover folded behind with the magnets now on the backside of the magnetic edge of the tablet. 

Although I can feel no magnetic attraction between the tablet and the cover magnets through the two layers of leather in this position, I have never experienced an unintentional sleep mode activation with the cover open to the left, nor did I in the week and a half I used the tablet prior to getting the case.

Although it's all circumstantial evidence at this point, I'm wondering if the magnetic latch on the tablet is so sensitive that merely having magnets in its vicinity is enough to trigger activation of the sleep mode.

If anyone else has had a similar experience, or perhaps some other evidence, I would like to hear about it.