I started always cutting the film because I observed this discharge about 30 years ago and it would fog the film. Recently, though, I noticed if you peel the tape slowly you can be OK. This pertains to re-spooling 120 to 620 rolls, where you need to release the tape and re-stick it.
Could be stress fog too. Take a piece of unexposed film, and put a crease in it. Develop the film. Bet you see some fog along the crease mark.
Cool. I saw this last night too. I went back to check my previously processed rolls of film and sure enough the image of the luminescence (mottled light grey) is clearly visible at the end of a roll of 120 of film (HP5+).
Now if my negative pressure ventilation system approached that of a vacuum, the process would be generating X-rays too ! Huh you say ? Well, check this out.
I take the tape off after I've spooled the film onto the reel. I do this because I don't like the chemicals seeping under the tape and not being fully rinsed out in the last step. My last step is four fill and dumps with progressively more inversions between each f&d. Also I don't like the feel of peeling off soggy tape !
I wonder why peeling off the tape would only emit x-rays in a vacuum and not at atmospheric pressures.