The switch had gone bad and I was sure this could be a fire hazard. Opening the switch confirmed my fear. The home is now 10 years old and the switches began to fail at the 8 year mark.
I have lived in homes with switches that must have been 40 + years old and never a failure. New homes have many more switches and outlets than the one I grew up in. The large quantity of switches and the abundance of cheap imports may both contribute to any single home experiencing this type of failure.
So don’t delay replacing the switch if you experience this issue. Of course, turn off the power to the switch before you make the repair.