2013 Slim, with original battery, and H-D Combination Analog Speedometer/Tachometer

Last November I started seeing a strange anomoly.
Whenever I'd top off my tank the digital gauge would only read 7/8 full, with the occasional "VINERR" message in the readout.
This continued for a couple of months.
I finally decided to take it to the dealer before winter storage, and on the way there the gauge jumped up to full.
I turned around, went home and canceled the appointment.
I put it away for the winter with a full tank without looking further.
First ride this spring, I noticed that the fuel gauge was now working properly, in fact I've never seen the "7/8 full" issue again.

However, the VINERR issue still exists.
On cold starts, the bike will (sorta) crank once, then hesitate, before cranking and starting normally - followed by the VINERR display.
Once it's warm, no issues - this only happens on cold starts, like when it sat overnight - and it doesn't do it every time.
Otherwise the crank is strong and the bike start within 2-3 seconds.

Google brings up may ideas, most of which say to check for a low battery.
That sounds reasonable since it's still the original battery.
But yesterday, I yanked it and took it to Advance Auto & Batteries Plus to have it load tested.
Both places said the battery was fine, showing 13V and 300+ CCA.
All connections and grounds have already been checked and cleaned.
Any other ideas of what to look for - or is my ECM going bad?

 

I get that sometimes with my Fat Boy S. I have my key and fob in my back pocket and wondered if it's because I'm sitting on it. I stand up and then the code goes away and the bike starts.