WB flash preset value in-camera

Hi,

I'm struggling to understand the colour temperature figure which appears to be set when using the "flash" setting in-camera on my K-7. According to the handbook, this should be a figure of around 5400K. I normally use the "Auto" setting, shoot raw, and fine tune it later as required in Capture 1. I did a portrait session a couple of days ago, lit entirely using studio heads, which, according to the technical specs have a temperature of 5650. I used the "flash" WB preset in the camera for a change, rather than "auto".

When I look at these shots in Capture 1, the "as shot" WB setting appears to be 7450K and a tint of 16. This gives the images quite a warm reddish magenta tint. If I set C1 to use its own preset "flash" WB it sets the figures to 5250K and tint 2, which looks somewhat green to my eyes.

The walls of the room were relatively neutral, a sort of light mushroom colour, which may have affected the result, but I still don't see why the in-camera flash WB figure appears to be so high. I checked to see that I hadn't inadvertently fine tuned the WB setting for the flash, but I hadn't, it was still on the default figure.

I'm using a good monitor which has been hardware calibrated so I think we can rule that out.

If I check the image using the bundled Pentax software, I can't read the "as shot" figures directly, but it does tell me it used the "flash" preset, and the image does still look reddish.

Any clues? Do other K-7s set the flash WB to such a figure? It does seem to contradict the handbook, and the expected setting.

There are different lamps with different colour temperature, I simply use auto WB since that works quite well.
With portrait you can get the white balance quite well from someone eye white so I use that but a card is better of course.