Orange fireball with strange movement

It was about mid February 1984 at about 10 or 11 pm traveling south on Route 10 in Marlow NH heading to Harrisville, NH.  I decided to take a back road and turned left or west onto Route 123.  As I made the turn I observed what appeared to be a barn a top a hill fully engulfed in flame.  I pulled to the side of the road to take a look and thought I observed the fire move. I thought I must have been moving so I stopped dead still and I observed movement of the fireball.  That scared me because this type thing is not suppose to happen.  I did a U-turn on Route 123 and as I headed back south on Route 10, looking back once and observed unusaul movement again.  I stepped on the gas peddle and got away as fast as I could.  I considered reporting this to the police but figured it would just get a big laugh.  In about 1992, when I was back in the area with my Mom, Dad, and fiance' I drove back to the area, retracing my drive. I found there was no hill that could have supported a structure on fire in that area.  I graduated with an environmental science degree in May 1984 and am currently a stable husband and father and business owner.
Witness indicates that the date of the sighting is approximate.  PD