I have finished processing the Barnard 169 and 171 image on June 11th, and have noticed there's a new object there… It's a 16.5 min. by 1 min. swirling snake of red (mainly) and gray/blue, that resembles a shock wave as visible in other objects – running from east to west, a little to the north of Barnard 171 (you will easily spot it at the top-center part of this image).
After checking all the raw images, including those of the next night out, and all the flats, I am rather convinced this isn't any artifact… However, I have called some colleagues to the task of shooting additional images of the area, with (J2000) coordinates: RA 21 58 53 DEC 58 46 04
I have also sent my report to IAU later that day, with full details.
Will keep you posted on how this develops.