Your fear that she is mad is your fear and your thought only.
She has her very own thoughts.
She has the capability, the ability, and the responsibility for her end of the therapeutic relationship and she could have said no to your asking if you could say something, but she didn't because she choose to, decided on her own, to listen to what you had to say right then.

She is aware of your intense feelings about her being gone. Being away from T is hard enough and the longer it is the harder it is. I told T once that time=distance when I am away from her, and it intensifies the anxious feelings. (She agreed). So, when time AND distance are involved, it is very hard, very intense in our minds.

I think her saying yes to your request to say something was a way of offering you a bit of reassurance. Can you think of that as her being kind and reassuring because she understands how you feel about her being away?

It is hard.