Juve had used two subs and Del Piero was stripped and about to come on as the third sub.
At this point, Aquilani informed the Juve bench that he had a minor injury and thought he ought to come off as a precaution.
Del Piero went back to the bench and Salihimidzic came on for Aquilani.
There was nothing wrong with what happened and nothing would have been said had it not been Del Piero who was about to come on.