[Elecraft] KX3 ATU goes off/on during send?

[gt-i at gmx.net]

During ARRL-DX - running 5 watts -  I noticed a faint click in the KX3, 
occassionally. I tried to reproduce but couldn't. Later I noticed the 
ATU-sign was blinking briefly after the click.
I checked SWR, but KX3 says 1:1, and a quick ATU- tune confirms the 1:1.
I'm a alarmed now - I don't want to see my ATU in smoke. But I don't 
have a fix or workaround yet.
Anybody else experienced this problem?
tnx es 73
Gernot
DF5RF