Yes, there were always extremely faint traces of lane markings (white diamonds and a yellow centre line) in that part of the ROW, which I presume date from when the ROW originally opened. (Here's a
random photo where you can see various faint lane markings in the ROW.) However, the markings had almost completely faded away, so I was quite surprised to see them brightly repainted last week.
Edit: I'm sure people here know more about this than me, but it seems that the ROW south of College wasn't fully segregated when the line originally opened in 1997; other traffic was initially allowed to use the streetcar lanes outside of rush hour. After a large number of collisions, temporary barriers were put up, and then curbs were installed in 2000 to fully segregate the ROW (a
couple of
sources). The initial sharing of the lanes would explain the original lane markings, but it doesn't explain why they've now been repainted, after almost fading completely away.