I got the Hassy out of hiding today - as it has been months since I used her. Loaded a rather finicky roll of expired Delta 400 in the A12 back (which needed encouragement to lay flat under the flange) and went out to shoot this giant dead tree I have been eyeballing across the street from my son's Catholic School.

Around shot 6 - after exposing, I went to cock the shutter and it stopped. Both nodes were red (for film and body). When I got home, I took the film back off and the shutter cocked! I wound the film back and put it back on. I am now on shot 10 with no other signs of fail.

What caused this?

Could it be from lack of use?
Could it be from the film?
OR - could it be from me switching the O to T and test firing before I loaded the film (I was playing with my cable release as I have no idea how to use it before I loaded the film in). I made sure it was back to O before using the camera, though.

Thanks for your help!