D&RGW Narrow-gauge mileage c. 1963 - Question

Page 345 of Hilton's "American Narrow Gauge Railroads shows a most interesting tabulation of D&RG narrow-gauge mileage, by year, from it's beginnings in 1871 to the sale of the D&S in 1981. After conversion of the Monarch branch in 1956 mileage dropped to 264, Alamosa-Farmington and Silverton branch.
Beginning in 1963 the table shows an increase of four miles to 268. This is carried through until final abandonment in 1968. Question is, where did the extra four miles come from. There was surely no new construction or relocation at a time when the whole line was only a few years from abandonment. Did D&RGW acquire a mine or lumber spur that was previously private? Was operation resumed over some "dead" track as a result of the 1962 ICC decision to disallow abandonment of the Silverton branch? The CO. map in my book shows a very short unnamed branch running north from a point about 10 miles east of Durango. What was this line, and might it be the mileage in question?
Thanks in advance,
Jeff