I just watched about 2.5 quarters of the tape. There is something to this. It obviously isn't 100 percent, but if he licks his hands late in the play clock, there is a very good chance that he is passing. If he licks quickly as he gets to the line or not at all, I didn't see enough correlation to be considered a tell.
Of course-
1) The Bears generally pass regardless
2) Run plays are more likely to be run earlier in the play clock
3) By the time this "tell* becomes available, it's questionable how much the defense will be able to adjust to it.