Thanks all for these. I developed 3 rolls of Portra 400 within about a day with the same camera/lens combo. Only one roll had the leak. I do remember having some trouble loading one of the rolls into the reel and having to take it out and try again 3 or 4 times, which is really strange for me, as I've loaded hundreds of 120 rolls without difficult. I don't know what happened or whether it was that roll that produced these strange rings. Most of the photos came out unexceptional. Here:
Are you using plastic or metal reels? If plastic, do you get binding or are they operating smoothly? Also are the problem exposures always at the beginning or end of the roll, or are they found randomly?