My mother has appointed my brother as her Durable POA, Executor of her will, put him on her joint checking account (or accounts for all I know) and basically left me out of the loop. What can I do if i feel bitter about this?

I don't mind so much but am worried that if he dies or is not able to fulfill his duty and she is not competent to appoint someone else, what will happen? I have told her numerous times to please appoint me alternate, just alternate, on this papers. My brother has 7 more years to work and she is 81. She claims because I live in another state is the reason she did this but that is not the truth. She has a problem with trust and for no good reason. Are my concerns justified or should i just go about my life and forget it. I have already stated I will not seek guardianship if it comes to that. She has been warned,