Unlucky, lesson learned! dont be lazy!

I started a print for my next set of shelfs yesterday. It was going to be ~20 hour print. no big deal. i have done that plenty of times.  I usually print with a .4 nozzle, and have had good luck with PA12-CF in it.  I figured what the heck, it will be okay.. well, it wasn't. After around 18 hours i went to go check on the print, and it had a failure.  It started to air print. The only thing i can think of is that the .4 nozzle ended up getting clogged.  Has anyone else had failures with a .4 nozzle and carbon fiber filaments? This is the first time i have ever had a air print.  I got the print restarted, put a .8 nozzle in. The time for the print with .8 is around 17 hours with the same wall thickness (less walls, same final printed thickness) and a slightly higher layer height.