I just recently swapped out a 3B for a 3B+. Did up a fresh Micro SD card with the latest Raspbian, then did the usual sudo apt-get update and upgrade. Did them both twice actually. Everything seemed fine. Put that Pi away for a week or two.
I just fired it up again today and got the flashing lightning bolt? I hadn't noticed this after the original fresh install.
Checked my voltage at the GPIO and it was just a little under 4.9V. 4.86, 4.89 fluctuating a little bit. Power supply is 5V at 10A.
Scratching my head I did another sudo apt-get update and upgrade. No more warnings? So is this a glitch (false warning) in Raspbian for the 3B+ that's fixed by an update upgrade? If yes, any plans to roll this fix into a new release?
If there is a sticky on this I missed it, haven't found it yet?