There were two things, Richard discerned in the brief ten-minute rest he was able to obtain once Albert left off to somewhere.
First, he wasn't able to fool the people around him. Although he did his best to act like Richard he failed miserably. In the case of Albert, Richard guessed that he must have sensed the changes in him based on the irregularities he was showing on his magical side. For a magician, controlling Ether is like breathing...and Richard failed to keep it consistent.
The second thing was Albert's motive for this abduction. Richard had felt it before as well but now he was one hundred per cent sure.
Albert likes the Duchess.
He was alright with the fact that Bellarine was fawning over her son until now, however after Albert discerned that there was someone else inside that body and he was taking advantage of the Duchess, the butler lost his cool.