Fill-In Flash White Balance Dilemma

I've been taking some photos of a model outdoors, but in the dappled light of woodland. In order to obtain a good exposure of the model I used fill-in flash (Canon 40D, single spot focus on model's face). The resulting images give good exposure for the woodland and the model. However, when I post-process these images (using Canon's proprietry software or RawTherapy) I notice that the model's image does not change in the same way as the background. Is this because her exposure was via the fill-in flash, while the woodland was natural light? If so, apart from selecting the model part of the image and treating separatly, is there any other way of compensating for this effect?

David

Sounds to me like a white balance issue, as you also suspect, but it's difficult to assess without seeing examples. The white balance difference between your model and the background would have been much less pronounced in full daylight. I am not familiar with any simple way to correct this using post-processing alone, other than manually setting a different white balance based off each region in RAW, developing each separately, and then combining these later with a mask. Sometimes people use color filters on their flash to change the color temperature just a bit, which may or may not have been helpful in your case...and would require taking it all over again. I would just set the white balance for based on the model and let the background white balance be what it may...

Thanks for your reply. It looks as if I haven't missed anything obvious.

Very interesting, thanks for sharing.
I haven't stumbled across a similar problem yet.