K20D - Focusing screen fell out ! ! !

I shoot images for a racing club at our local oval race track and I usually use two cameras. K5 with Sigma 70-200mm for car action, and K20D with DA* 50-135mm for closeups of the winners.

Last night I was unable to use my K20D because the tray that holds the focussing screen became unclipped, dropped down, and the screen fell out into the mirror box, jamming the lens such that I couldn't remove it until I'd figured out what might have happened.

As the view in the viewfinder was looking very weird, I deduced that the above had happened, tipped the camera upside down and heard the screen moving inside and I was then able to remove the lens.

I couldn't refit it at the track due to lack of light, no tweezers handy, and numb fingers from the cold.

Once I got home it was easy to refit it but I noticed that the spring clip that latches the tray closed was not as positive as I thought it should be.

Anybody else had this problem?

BTW: I got all the photo's I needed by using only the Sigma lens, I just had to stand back a bit further

I've heard (and seen) the screen drop out when a camera has taken a bad knock but not just in normal use, might be worth having it looked at.

I could understand if it had had a hard knock, but it hasn't. I lat used it two weeks ago and it's been in my bag sitting on the bedroom floor ever since until I took it out yesterday.

Really odd.