I have *always* been worried about that. I carry a tip-up automatic in my back pocket next to my wallet, and I have formed a habit of checking it CONSTANTLY. I notice when I don't have it with me, everyone probably thinks I'm wearing a thong for the amount of times I "fix" my behind in a day.
I've poked myself with it a couple times, but nothing like that.
FWIW, I think an automatic knife is just sweet compared to a good assisted knife, it really becomes an extension of your body when there's no fiddling involved getting it open. Tip-up autos are the way to go