On the first image (1.jpg) the lines are not parallel to the frame edge. Unless it was rotated after scanning, this excludes he camera or processing machine. Taking a clue from: "on a previous roll of film, some of the negatives a tiny areas of hard congealed shiny almost 'varnish' type of substance on the edge of the film" I'd guess the lab had some processing issue and clumsily tried to wipe the film clean. Go to another lab if you have the choice; if you have no choice, try to politely educate them.