Was there a flanger train on 12/18/61?

Dear John et al -

I've been looking again at the third, fourth and fifth beautiful photos on JBWX' "Personal Favorites" web page at [chasingtrains.smugmug.com] and I noticed a faint smudge of what appears to be locomotive exhaust at the far left edge of all three photos. This couldn't be exhaust from the train that's the main subject of the photos 'cause it's way too far away from the lead locomotive, beyond the telegraphone poles to the left.  And it can't be clouds 'cause it's partly below the top of the mesa in the distance and changes shape too much between the first photo of the set and the third one.

I'm thinking that a flanger train probably ran ahead of the westbound freight that day, and the flanger train was climbing "Gravity Hill" while the freight was passing the yard-limit sign as it left Antonito. There's no date on the Antonito triptych, but I assume the three were taken the same day as the preceding photo on the three-rail south of Alamosa - which is dated 'December 18, 1961' - so maybe Jimmy Blouch can confirm my wild guess . . .    

- El Abuelo Histœrico, Greengo y Curmudgeoño de los Locomoturas Viejos y Verdes,
aka Der Grossväterlich DünkelOlivGrünDampfKesselMantelLiebHabender