Has anyone noticed?

I've never seen anything green on Bobby.



Annoying the world since 1960!

You must be talking about the episodes where Bobby has anger issues and shows signs of turning into the Incredible Hulk. It was planned to have an episode where Bobby finally loses his cool and turns into the Hulk, but it was ultimately scrapped because Mike Judge and the writers wanted to take a more realistic approach to the show.

Yes. Especially in some of the earlier episodes at least.

Composite TV hookups use red, blue and green (not primary yellow) to make all (or very very close to) the colors on TV. Perhaps you are seeing the "almost yellow" pigment.
??BACKSTABBING?? In the KOTH episode "Hank's Back" (on Cartoon Network) Hank describes a yoga position as "Modified Roger Staubach" but if you turn on the closed captioning the words "Modified Joe Theissman" has been typed in place of the spoken script! There is an evil (EVIL I say) closed captioner out there and there's no telling where he might strike next..
Galaxy Rangers...HHHHHOOOOOOOOO!!!