I don't see anything surprising about that. Lightning (not "lightening," btw) produces large amounts of airborne RFI (radio frequency interference). A good illustration of that is the static that can be heard on AM radios when lightning is in the area. Obviously a tuner (FM or AM) is designed to receive very low level radio frequency signals, and to greatly amplify them. So the tuner picked up a burst of RFI at high levels, amplified it some more, and the resulting transient in the circuitry was large enough, and at high enough frequencies, to couple (perhaps via stray capacitances in the circuit board) into some of the digital circuitry in the tuner, causing the result you observed.
As long as operation subsequently returned to normal, perhaps after cycling power off and then on, I wouldn't worry about it.
Regards,
-- Al
As long as operation subsequently returned to normal, perhaps after cycling power off and then on, I wouldn't worry about it.
Regards,
-- Al