Possible PVL?

So I had my son at 28+6 due to pre-e and pulmonary edema, and he was 3 lbs at birth and has been hitting all his milestones so far. He is now 35+2 adjusted and the nurse practitioner has just informed us that his ultrasound today shows signs of PVL. I'm really confused because he seemed to be doing just fine up until now, he has moved to an open crib and is only on 2L of oxygen and I thought we would be smooth sailing until we left. He hasn't had any complications his entire stay so far so I'm confused as to what could have caused this.

Anyone have experience with PVL and how did it turn out?