M14x - Strange but true!!!

Hello all, this post is more about odd laptop behaviour than tech support, I've repaired quite a few M14x over the past few months and today I recieved one that gave me a suprise, when I plugging in the AC adapter, the light surrounding the touchpad start slowly flashing on and off, exactly the same as the "alienhead" power button light does when the battery is charging, the laptop is working fine, no faults at all, just odd behaviour I hav'nt seen before

Has anyone else experienced this?

Cheers

Andrew