T610 Unlock Keys Oddity...

My keys are locked. If I press the "C" key whilst they are locked, I get the
"Press * to unlock keys" message.
Sometimes it displays the message in a larger-than-usual font. Still
perfectly readable, but just bigger.

This only seems to happen occasionally, almost at random, but I've noticed
it twice today.

Strange? Or am I going slowly insane?

Scott