Getting CHT's that close on a carb'd engine is unusual, so I'd suspect a bit of luck with your intake leak. On my O-360-A1A RV, my climb out CHT's would be spread by 30-50 degrees typically, and in cruise they would run 15-20 degrees apart, using 1300 EGT temps. That was my best economy setting. Full engine monitoring can sometimes be a "bane of existence" type of thing...fantastic tool, but can make things seem suspicious that aren't necessarily so.