Hey, I had the exact same thing with a 4AD transdermal I mixed up a couple of weeks ago. Also heated it (don't know how else to dissolve it anyway).
Bought it just before the ban in february last year. Did you also kept it in the freezer?
Another thing that crossed my mind was that it wasn't so much the 4AD that caused the orange color, but the transport matrix. Maybe something with that particular batch? I bought the matrix about two months ago. You?
Anyway, I have used it already and noticed no difference, no strange or bad symptomes like turning yellow or something either.