I spoke with one of my colleagues about your problem.  He said that he's never seen the problem as you describe it either, but if it happens regularly, you should send it in for us to take a look at.  If you see it again, just turning your H9 off and on again may help, but it's hard to say for sure as we haven't seen this firsthand.

In any case hopefully, it was just related to the power at the venue you played at, but if you do see it again in the future, you can email support@eventide.com to let us know.