Lexus LS 2007+ :: LS460 Seat Belt Buckle Light?

For the first time I noticed a little glowing light[s] in my drivers seat belt buckle [female end....actually 2 lights, one on each side of the female part where the male end inserts]. It glows for about 10 seconds when starting up. Probably useful for connecting seat belt in the dark. What it does at night under normal driving conditions.

I did not see the same light on the passengers' side. Don't know if there is not one or it only works when there is weight in the seat.

Esoteric little item....but just wondering if there should be the same light on the passenger side and , if so, where /how to troubleshoot? Would it be a bulb or built in to the buckle? I did not check rear seat....I will do that next...