Out of curiousity, how often do people find the eInk side needs to be recalibrated? Has anyone had any issues requiring frequent recalibration? I ask because I feel as though opening certain files (or even just time... maybe over the span of a few days) seems to cause the eInk screen to respond differently than it should (sometimes the line I draw appears 1+mm away from the stylus). Just curious if anyone else had experienced this or if it was normal.