derekl

By default, the X-T2 has White Balance assigned to the right selector button. Pressing the selector right once brings up the white balance menu. If you're already in auto white balance then another press of the right selector button takes you to the WB Shift screen. More presses to the right will push the white balance shift towards the red end.
 
It seems entirely reasonable that unknowingly/accidentally pressing right several times would cause the white balance to shift. Only pressing the BACK button or turning the camera off will cancel the accidental white balance shift, but pressing your shutter release is the same as pressing OK, so that would accidentally lock in the WB shift changes =(
 
I personally don't change white balance that much and removed white balance from the right selector button. If you need quick access to white balance, I would suggest assigning it to function button 1 (between shutter speed dial and exposure comp dial) or to the My Menu.

Menu -> White Balance -> Auto ->
 
Now you are at the "WB SHIFT" screen: you have two axis, more yellow or more blue, and more green or more red.
 
Mine is set to R=1 and B=-1.

I don't have an XT-2 - but do have an XT-10.  But I sometimes get the same problem - reddish/pink files.
I'm shooting normally and the colour balance is OK - and then all of a sudden pink pictures.  If I enter the colour menus I see that the grid has moved to the far right (pink/red) side.
Somewhere in the buttons there's one that automatically seems to do this.  I haven't discovered which one it is.  The buttons on the back a quite small and it's easy to press one by mistake and change an all important setting.
I wouldn't mind betting that this is what you are doing - pressing a button inadvertantly
 
David