Nexus 7 4.2.1 jelly Bean = Does not sleep with 15 seconds - 30 minute inactivity

i noticed that after installing the jelly bean update 4.2.1 the device does not sleep with even 15 second of inactivity. what gives?

and the wifi is still on even when I press power to go to standby (and I unchecked keep wifi on during sleep) :-!

Settings---> Display---> Sleep---> Select the preferred sleep time.

Sent from my Nexus 7 using Android Central Forums

Some apps can keep the tablet awake. If the app is malfunctioning, it could conceivably cause your problem.