After some more checking it's related to times being sunset related - all my modes that are triggered by sunset, or later of two times including sunset, are ignoring day of week restrictions:
It started after I updated from 2.3.1.142 to 2.3.2.135, and it continues to do it while I am at version 2.3.2.141.
I found that having earlier of two times configured fails to change the mode after the latest update ( I had sunrise and 7am ). This had been working consistently since winter. As a work around I changed to just sunrise, which is currently working.
@bravenel BTW this is not fixed in the current release, but I've migrated away from the Legacy Mode Manager to the new one, and everything works fine in the new one.
So I am no longer affected, but I still have my Legacy Mode Manager setup installed if you want a copy of it. Let me know.