(Image source from: New Umpiring Signs In Cricket})

Don't be surprised if a umpire places a finger close to his chest while referring a doubtful decision to the TV referee in coming new ODI matches,the signal indicates that umpire in doubt whether batsman is out but seeking the opinion of other umpire up in the box.

New umpiring signs are introduced by International Cricket Council (ICC) from October 1 2014.These signs were introduced to provide greater clarity for spectators and make ground umpires more pro-active.

Bringing more clarity,transparency from spectators point of view and to reduce the mistakes of the ground umpire signs were introduced. sources

According to the new playing conditions, if there is a bump catch, doubtful catch or obstruction by a fielder, the ground umpire will consult the TV umpire by making a TV-screen sign as they do while referring a run out or stumping. After that, umpire has to flash the out or not out sign with the finger close to the chest.

Beyond that except bowler using illegal action and whether bats man hits the ball,umpire will check other actions of fairness, while reviewing TV replays.  

(Aw : Arunkumar)