"Dr." Jon Goodman of foam reseal kit fame has diagnosed the problem thusly (w/ permission):
"Thanks for the note. I have attached the re-sealing instructions for the 35SP, but I don't really think you are suffering a light leak. The reason I say that is the damage on your scans is all whitish/grayish in nature, and the pictures seem to be generally over-exposed by a stop or so, maybe a bit less. For this reason, I am thinking you have either a lens flare/glare problem combined possibly with a meter problem (and the meter in the 35SP is a design which can have problems as it ages). With color negative film, light striking the front side of the film will produce a whitish/grayish damage whereas light striking the back side will produce orange/yellow/red damage. Light striking the back causes the color layers to react first, where light striking the front side simply tells the film to overexpose indiscriminately. Were you using a hood or filter of any kind? I would try a UV filter or a short hood (maybe 3/4 of an inch to an inch and a half) if you can find one. You seem to be getting too much light on the film first of all (a meter problem), and second to that, the very center of the lens seems to be picking up light and making a flare spot out of it. Were these shots taken when the sun was high overhead? I'll be interested to hear." Note: I used a hood.
and as p.s:
" I'm not convinced the meter design was as good as the sales data claimed at all. Comparing it to meters in Minoltas, Canons, Yashicas, Konicas, it is slower and less accurate. Not really a criticism as much as an observation".