You've changed vs you changed

[B45]

I haven't seen my wife's friend Annie in a month or so, and she dyed her hair platinum blond. I say to her:

"Hey, love your new hair color, you've changed it to such a bright shade!"

VS

"Hey, love your new hair color, you changed it to such a bright shade!"

Are both useable here? What would a native speaker say?

 

[MikeNewYork]

Both are possible. Because it evidently happened within the last month, I would probably use "you've changed".

 

[Tdol]

If the comment is being made on seeing it for the first, then it's the present perfect for me too.