My old manager fell out with me on my last day.
She was an extremely volatile person; she couldn't hide her (frequent) bad moods and when she was in one it but a downer on the whole team.
My last day was near Christmas and the whole office had a Christmas party that started after lunch. We were on our way to the party, in a group, and she was talking about this new film by her favourite director. I said I had seen it the weekend before and hadn't liked it very much. She snapped a bit, but she was a snappy sort of person, so I didn't think much of it.
It became apparent over the course of the party that she was blanking me. We were sitting together in our small team the whole time so it was obvious, and noticed by others.
She left early under the guise of 'going for a cigarette' at the same time as someone who was leaving early. She never came back in, never said she was leaving, never said goodbye to me, never said good luck in your new job, nothing.
I was very young at the time and felt awful, and was upset. A colleague who had noticed her coldness comforted me and told me a few stories about her.
Manager emailed the next day saying that she had left because she 'didn't feel well'. Never saw her again.