Here's an update to the disassembly issue. It turns out that my gun was equipped with a NY1 trigger. It happens to be a heavier trigger used by the NYPD and the NYS Troopers. Instead of the standard 5.5 lb pull, it had an approx 8 lb pull. A side effect of this heavier trigger is that the trigger bar is pulled up by the heavier spring and the trigger bar gets caught on the slide when attempting to remove the slide. That is why the trigger had to be pulled again to release the slide. I've had the trigger replaced with a standard Glock trigger and the problem has gone away.