Normal and Abnormal Temperature for Nexus 7?

Mine sits at around 80F +/- 5F but anything over 110F I stop using and let it cool for afew minutes.
 
If you mean the warming of the powerful multi-core processor, no need to worry about ... unless its heat affects the battery's temperature.
What you'd look it's the battery's temperature ... because it's the tablet's most sensitive component.
That's not dependent on the tablet's brand.

The Li-Ion battery's allowed max temperature is for discharging 60C (140F) and for charging 45C (113F).
If the battery remains below this temperatures that means it doesn't represent any danger.
But high temperatures of the battery over extended periods of time will decrease the battery's lifetime.