One was former ASA who had gone to Continental and didn't like it, so decided to come back (That was weird to me too, but different strokes for different folks).
Didn't like it, eh? Probably more like fired, furloughed, etc.
Before your probationary period is up, they will give you a chance to "resign" so nothing is on your record for future aviation jobs. This way you can say in an interview that you resigned for whatever reason you want and there is no way to find out. Essentially you are correct in your first assumption though.