I cannot escape this thing! I did put a print statement inside a loop (different sketch) It essentially turns on a LED 20 times
i.e. for (int i = 0; i < 20; i ++)
... Blink the LED
... wait 3 seconds and do it again
I inserted Serial.println(i+1); inside the loop.
The error in the output only occurs on the first pass. After that I get 1...20 as expected.
Don't believe it's a hardware issue.