Cal vs. Arizona St. - INADVERTENT SIGNAL??

[GPC2]

On a punt late in the 2nd Quarter, a Cal player fielded a punt and was immediately tackled. On the tackle he fumbled the ball. At the moment of the tackle the BJ gave the signal to kill the clock (w/o an audible whistle). There was a scramble for the ball and the BJ continued to officiate (following the scramble), but gave the signal at least one other time (again w/o an audible whistle). The R anounced that the ruling on the field was that the punt was caught and fumbled and recovered by the kicking team. The play was then reviewed and after the review the R said that there was an "Inadvertent Signal" on the play, and by rule the receiving team retained possession at the spot where the receiver caught the punt.

My question - is there such a thing as an Inadvertent Signal under NCAA rules - and if there is, is it treated much like an Inadvertent Whistle?