Mine just started doing that two days ago. It's very intermittent, but it's damned annoying
ESD can cause strange EMI problems. The discharge doesn't
need to be to/from the keyboard for there to be problems.
One simple way to generate a nice wideband EMI source is
to use a coil/solenoid and energize it with a D-cell battery.
Holding one side of the connection steady, keep making
and breaking the other connection so that you generate sparks.
If you do this near your keyboard and it causes problems then
you have demonstrated an EMC problem, and one possible
reason for the keyboard to experience strange symptoms.
I've heard of products suffering resets and other problems from
simply moving your body on a cloth seat - I've seen this personally
as well. At least here in the frozen north, this time of year is when
these issues will show as the humidity is so low that ESD is much
more frequent and energetic.
Try it out! Post your results!
Another possible solution: Put a humidifier in your room and see
if the problem goes away.