Default Nexus 7 deepsleeping while charging?

As the title says I'm a little confused about the way how nexus 7 acts when charging. I have never even noticed this thing before but it seems that my nexus 7 is sleeping while it charges. I have tried many combinations like stock ROM+stock kernel , cm11+cm kernel, cm11+ franco and cm11+M-kernel. Every time I check cpu spy I see that device has been almost all time deepsleeping. I'm using the stock charger.
Here's example screenshot (sort period yes, but there you can see it):

I've read many forums and I have experiences with other devices that deepsleep shouldn't be there during charging due charging process. Device works otherwise fine and it charges normally but I'm just wondering if something is wrong on the hardware side. Some information and experiences with other nexus 7 devices would be highly appreciated! I know this is almost meaningless thing, but I'm just curious to know if this is some kind of feature of nexus 7 or if I just have sleepy unit
Thank you!

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