Mine has done this too over the past 2 years (the xenon headlamps, but not the fogs) - I started a thread on this a while back because its almost always both at the same time - I replaced one of the ballasts and not sure why but it seems to happen less often now, hasn't happened in a while actually -

I have a newer alternator and battery and LED tail lamp units which are 6+ years old now and working fine, I just chalk it up to an occasional electrical gremlin -

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2018 Ram 2500 6.7L Cummins 68RFE
19k miles -Bright White/Black - Big Horn Sport - Crew Cab Short Bed
2013 X5 35D (CEO's) - Born on 5/17/2013 -
82k miles - Alpine White/Cinnamon Brown/Premium Pkg, Sport Activity/Premium Pkg and Sound/20" Style 214/Running Boards