I've got a couple of calls in my call log which I'm pretty sure were never made - one of the was to my other number which didn't ring or record a missed call. I kind of assumed it was because the screen lock was activating and setting off the phone app... but now I'm not so sure. It seems to be capable of randomly selecting contact from the list.

I too have been making sure I lock the screen before putting the phone away - but I still often find that it has opened, and selected a contact when I take it out of its pocket.

Thank heavens I don't have any international numbers in my list!