Is the boat in or out of the water? The mast step looks pretty good to me. Take a bottle of water up there and pour it around the mast step. It should not pool. Pooling might indicate depression of the mast step relative to the deck. That would warrant a look under the compression post. Also look at the turn buckles. If they are adjusted tight the boat could be deformed temporally. Also if the turn buckles are near the max of their range, it could indicate continual tightening as the deck deforms under the compressive load.