By the time we went to bed last night, we had begun to think the toilet problem had worked itself out.
Alas, it had not.
The whining woke both of us early this morning (5:30 ish?). It continued through the day, but I began to suspect that it is actually the shower causing the problems / noise. As soon as the water in the shower turns on, the sounds stops. So if it continues, we may have the “peaceful” sound of running water in the background – a slow shower flow :)