Actually he could think of dozens of people whose word he would accept without question, she just wasn't one of those. Naturally she was very carefully watched as she moved to stand and the Doctor ever so helpfully cheered her on with a quick recorder solo of 'The Old Gray Mare'... until he watched a little more closely and noticed it seemed to be more recent injury than old age catching up with her.

"You've forgotten your radio."

Which was speak for you needn't rush off with out it.

"Did you take a tumble when you arrived?"