Question about the Maer's medicine (Spoilers inside) Rereading for the third time. Starting to pick at parts that bug me.

Kvothe proves that he is bringing the maer Caudicus' poison by feeding the birds a poison that *he brought up to the Maer himself*.

What reason does the Maer have to believe that Kvothe hadn't simply poisoned the 'medicine' himself enroute?