The first example happens all the time.
The second example just happened a few minutes ago - I felt a wave of sadness. It always throws me sideways because I don’t know why it’s happening. Sometimes I get a trace/accent attached to the feeling though. It’s Friday afternoon where I live right now. Weekends were always extra bad when I was growing up, and I used to dread them. I think my teenage Alter (Munro) just got sad because of that, and because she’s very much stuck in the 80’s when I was a teenager as well.