Pressing against a machine in an awkward seated position usually causes an elevation, protraction, and internal rotation at the shoulder that’s not ideal for shoulder health and pressing proficiency. Bring the elbows down and stabilize better by using the thumbless grip. This simple adjustment will minimize the compounded joint stress from this machine.
One last note on machine training in general: Make sure you optimize your setup by fitting the adjustments to your body. For the chest press, the seat must be elevated to a level where the pressing handles sit about at your nipple line. Above or below will deter away from the trainability of this movement, and should only be utilized strategically for accessory pressing movements or isolation training.