I would guess it’s an older guitar, and a special one if Paul was attending to it. Celtic knots were made unavailable since the launch of the Collection Series sometime 2011. And that’s the unmistakable European maple top and stain of the Violin 1 run which was like a 2009/2010 ish timeline. PRS did not have many of these European maple tops outside of the Violin 1 run. These maple tops have a unique “loops within the flame” look. I’m guessing this was some special one-off guitar that had its trem upgraded.