Weird NEST thermostat issue

I know we have some folks here with NEST thermostats.  I've loved ours for years and it's worked flawlessly since installed, but in the last month it's started giving me fits. 

Anybody else experiencing this issue?  It only started about 3-4 weeks ago, with no known prompting from us:

Randomly, in the middle of the day, it spontaneously sets the heat to 72 degrees.  Normal setpoint is 68 degrees.

• We have a daily schedule programmed - 68 dF from 6:00a to 11:00p, then set back to 64 dF overnight - every day of the week.
• The 72dF set happens randomly some time between 9:00a and noon.
• We have learning mode disabled.
• Looking at the history, it says the 72 dF was "Set by your adjustment".
• We have never, ever, not once, set the heat as high as 72 dF ourselves, and the cats can't reach the thermostat.

Any thoughts?

No solution but mine occasionally does that as well. I manually adjust it back to where it should be and it seems fine for a while. Only happens once or twice a year. 

EvanB said:

No solution but mine occasionally does that as well. I manually adjust it back to where it should be and it seems fine for a while. Only happens once or twice a year. 

Thanks.  We have never had an issue with it before (maybe 5 years?), but in the last couple weeks it has happened almost every day.  Always 72 dF.

In reply to Duke :

Does it have a battery backup or only hardwired? Weird thought, but a dying battery could mess thing up.

Or maybe a neighbor got a new remote controlled one?

In reply to RevRico :

I haven't had it off the wall since I installed it.  IIRC it is hardwired power only.  It's on our wifi, which is secured.

Our Nest doorbell very occasionally goes offline until I cycle the power to it.  Maybe that will cure the thermostat.

We've had one for about 5 years and I've never noticed that issue.  OTOH, it's typically set to 71 F during the day and the wife occasionally bumps it to 72 F, so maybe I just haven't noticed.

In reply to Duke :

Test the power by popping it off the wall and charge the battery via the USB port on the back.

We've noticed weird behavior after extended power outages. Once I remotely charge the Nest, all weirdness goes away.

In reply to myf16n :

I'll give that a shot.  Thanks.