Ruger recently discovered that all Mark IV™ pistols (including 22/45™ models) manufactured prior to June 1, 2017 have the potential to discharge unintentionally if the safety is not utilized correctly. In particular, if the trigger is pulled while the safety lever is midway between the “safe” and “fire” positions (that is, the safety is not fully engaged or fully disengaged), then the pistol may not fire when the trigger is pulled. However, if the trigger is released and the safety lever is then moved from the mid position to the “fire” position, the pistol may fire at that time. View Safety Bulletin PDF
I would say if it wasn't for the fact that the trigger was released before moving up to the fire position this would be normal. But being that even if you let go of the trigger and then move to fire that's a pretty big deal. That means that essentially your safety acts as a trigger.
I was about this say this isn't new. They have had this recall ongoing for some time now. For what it's worth I picked up the Mark IV earlier this year (great gun btw) but the serial number was post-recall so I was good to go.