digital caliper "skipping"?

Digital caliper...when I opened it yesterday, I watched the numbers and at one point the numbers hit a 'dead spot' and them picked up again, throwing the measurement off. I tried it a few more times and then it seemed to clear and is working again. WTH? Was it moisture (damp garage) or just lack of use? There is no gears in this, I think it just rides over some sort of hall effect sensor or something? Old trusty mechanical gauge caliper proved the digital was off, then it proved it was accurate once it cleared.....