[Elecraft] [k3] Tone/"Low Bat" indication?

[S Sacco]

I was working a station on 40M CW (qsk) this afternoon, and suddenly - and
only for a moment, my K3 got stuck and put a high pitched tone into the
speaker, while at the same time, indication "Low Bat" (perhaps "Low
Batt"?).  It then returned to normal operation.

I've experienced this "getting stuck" thing a few times, but never looked at
the display while it was happening.

I'm running 3.04 right now.

Has anyone seen this behavior?  If so, is there a way to address it?

Thank you & 73,

Steve
NN4X
EL98jh