I was in bed, watching TV, when I noticed an unfamiliar clicking sound. It
persisted, so I leaned over and saw my Fluke 87's backlight flickering, and
heard it clicking. (The knob was in the off position, by the way.) Turning
it on, then off, ended this weird behavior.

The battery enunciator has been coming on lately, so I have to assume it's a
side-effect of low voltage.

--
"We already know the answers -- we just haven't asked the right
questions." -- Edwin Land