I recently shot a stage where the start position was facing up range.
Make ready - I faced down range took a sight picture, loaded the gun and holstered it.
I turned up range to the star position and before the "ARE YOU READY came, I pulled the gun up from the holster 1 inch to ensure it wasn't catching, just as I often do when facing down range.
MD was right there and gave me a warning that I could not do that, even though the gun didn't clear the holster, even though it didn't break the 180. He didn't DQ me, I thanked him and told him that I didn't even know that was a rule, but it makes sense now because had the gun cleared the holster the muzzle had a better chance of breaking the 180, etc.