Alfred Hitchcock’s secret cameo?

In North by Northwest (1959) there is a short sequence onboard the train where an old lady has her ticket checked by a pair of rail guards. After a brief exchange of words, the guards move on and the lady half turns to the camera and gives a slightly comical shrug of the shoulders.

Hitchcock had already made a cameo near the start of the film. However, did he decide to play one of his many practical jokes by slipping into a blue dress to make a second cameo in drag?

Although the lady does indeed bear a resemblance to Hitchcock, the role was actually played by actress Jesslyn Fax (who had already appeared in Rear Window and in some episodes of Alfred Hitchcock Presents).

(Via)