Had it happen once in our 2016 Excursion. Just a few seconds while driving and as you said no issues with drive ability other than no speedometer or guage read outs. Decatur checked it but couldn't find a problem when everything was working. I suspect it's a Freightliner issue once identifie. Appreciate you putting it on forum. I'll add to the thread if ours repeats.

We have a 2017 pace arrow 38k and I noticed while driving through a light snow storm near Reno during our maiden voyage, the lights on the instrument gauges  flickered.  I trying to adjust the brightness which didn't help.  All the gauges worked but it's hard to see them when it's dark and when they flicker off.  I called freightliner while on the trip and they know about the issue but they don't have a fix for the problem at this time (10/10/16).  They did get my info so they can notice me when the fix is available.  Apparently they said it's a software issue.