Well, I was forced to issue formal apologies to my Nest thermostat.  The furnace ran all day without another issue - until it didn't.  I noticed as I ate dinner it was started to get cool.  Looked at the thermostat and I was at 65 (recall it should be at 68 during the day).  Went back downstairs and there is the code that was absent earlier today - six short, one long... it doesn't escape me that this is the cruise ship emergency horn pattern as well.

The internet (which cannot be trusted based on some of my recent searches indicating that 2/3 of an inch is equal to 7/16, but I digress) says on my furnace this means a faulty ignition system, gas supply issues, pressure switch problems, or thermostat problems.  I'm pretty sure the gas is good.  The thermostat is saying it's supposed to be running.  I have had issues w/ the pressure switch before.

Regardless, the HVAC folks are on their way.  Wish me luck.