AF point failure?

Has anyone come across a problem with the K10D and one of the AF points?
Well I say a problem, but it's more of an inconvenience.

Last week in London, I had my K10D and was shooting accordingly.
Now if you can visualise the Pentax AF points (of course we can! LOL)
The nine square cross haired points in the middle area, the left middle - one to the left of the centre point, will not focus. I only had one lens with me, but I would be very surprised if it was the lens.
Like I say an inconvenience rather than a major issue - the others were fine.

Thoughts?

I had a slightly different problem - the (same, i.e. left of centre) AF point light stopped working. An irritation, as I use these points regularly for focus position (rather than recomposing), and for focus confirmation.

I never sent the camera away or tried to repair it, as about three months later it started to work again, at first dimly, then back to normal. It's been perfect ever since.