Like others have said... transference is normal.
I think in regards to therapy (and keep in mind, I am in NO WAY an expert!) it would be more "transference" when the T is playing a much bigger role in your life, thoughts and feelings than just the role of a T.
So how you like that your T is always supportive of you and gives you undivided attention? That's just normal feelings because yeah, that's your Ts job!
But feeling that T is your best friend? I, personally, would think that that's more transference because you would be blending T out of his job and into a new role - much like how when people consider their T to be a mother-figure, that's transference because no matter how awesome the T is.. that T will never actually be the mother of the client - they are just fulfilling that need which is transference.
That's how I understand it anyway