Apple :: Yellow Lights When Looking Through The Vents

i've been playing far cry 2 for 4 hours. i shut down the game, my temp is 79-80 degrees celcius which is perfectly normal when gaming on the macbook pro. i don't know why i wanted to look through the vents. i turn my laptop and look through. i saw this yellow light. its approximately under the R and F keys on the keyboard. i turn my laptop and look closely on the keyboard and it's illuminated white. no sign of the yellow light. Thus, to resume, i saw it only when looking through the vents. does anybody know what is this light? what is causing it to light up? i smelled closely but no burning smell. in fact, i cant smell any weird odour. is it harmful for my macbook pro?

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