I Made SMBC for the first time today, and it turned out lovely, tasted great and everything. The final product however, turned out to be a gray color not white. Has this ever happened to anyone else? I am not sure why it turned out this color!?
Nope. The only thing I can think of is that something you were using to mix it in or stir it with transferred color to the SMBC or reacted badly to the ingredients. Could have been something from another project lodged in the head of your mixer where the metal beaters lock to the head of the mixer and became dislodged and fell into the buttercream.
This has happened to me before make sure that the paddle is not hitting your bowl. If it is that is what is causing your bc to turn gray.
Yep, sounds like tarnish. Won't hurt you, though.