Object seen in the sky west of Medford Oregon.

I was watching a plane in the sky to the west of medford oregon that had a vapor trail folloowing it. I looked behind the airplane  and saw a light that was traveling about the same speed as the plane and same height ,but it did not have a vapor trail. The sun was just setting and it looked like the sun was reflexing off this object and suddenly it disapeared. I watch to see if i could see an object thinking that it was not in the path to reflex the sun and there was nothing. This object appeared to be behind the plane by a mile or so.