I don't think you're strange at all. I have these thoughts at the oddest times myself. If it wasn't spontaneous I would wonder if it was a tool I used to gauge how I was feeling. But as in your case I'll be sitting there reading, watching TV, on the computer or whatever and those thoughts just pop in my head. I used to wonder "where did that come from?" and get very concerned that perhaps I wasn't in as good of a place as I thought I was.

It's hard to verbalize this in a way that isn't triggering. But basically I've decided that as long as I am able to answer those thoughts in the negative (as in I do not want to act on these feelings) and I'm able to pluck something positive from the air to be grateful for I'm fine. If those negative thoughts ever become more attractive I will definitely let my doctor know.