Old mobile numbers are recycled remarkably quickly. It's not at all unusual for people to get calls intended for the previous user of their number.
I've had my present number for around 15 years but I still get calls for 'Norman Hobbs' and 'Debbie England' fairly often. (I suspect that it was Norman Hobbs who called me, not long after I'd bought the phone that the number came with, accusing me of nicking his girlfriend's phone and telling me that he knew where I lived and that he was going to beat me to a pulp!)