Here's the sequence of events:
- I'm listing to a podcast via the relatively new podcast app.
- I pause the podcast.
- Time passes. The phone sleeps.
- I get a call which I do not pick up; I don't even touch the phone.
- The podcast resumes playing, surprising me and those around me.
This would be expected behavior except for item 2. I think it's a bug.
I'm running iOS 6.0, but this has been happening for a while; at least since 5.something. It's possible that it began happening when I started using the new podcast app instead of the music app for podcasts.