Awesome :) - though not a super helpful error as this is a Unity problem with the way it renders text likely (thus explains the rareness).
I've put some extra checks in place to tidy up/clear off text - so download the windows version 1.13b and see if those extra checks/tidy up fix it. If it sticks again, there's a checkbox under settings for "Fading Text" - that will simplify the typing animation, which should reduce the amount of processing it does, but not super confident that'll fix it.
*Fingers crossed*