Not exactly. He just sees's them, and he's like: "OMG that's a really different color version of [insert Pokemon's Name here]!" And then when he gets used to it, he's going to say: "Meh, it might be a different color than [Pokemon's Name], but I'm not going to catch it, I'll just let it be free."
In short, Ash never acknowledge shinies, partly because I think 1) He doesn't know what a shiny is when he's seen one, and 2) He doesn't care what color the Pokemon is, although he just wants to make friends with it or somewhat such.