See if the wheezing persists when flat and in his tank. Also look for discharge from his mouth/nose and or smears of mucus on the substrate (easy to see if it's paper).
What is your humidity level? Very important if worried about a respiratory infection (RI). Too low or too high can be bad.
Even if temps are on point, if humidity is off, that's not good.
How long were you holding Damian before he exhibited the wheezing noise?
My BP, Shayna, is a doll, but if I handle her for more than 15-20 minutes, she can get a little stressed and I've heard a little wheezing from her when she breathes heavy. I generally don't keep her out that long, and I have other snakes that "like" being handled more than her, but she will stress if out too long. She has no history of RI and does not currently have one. However, several times in the past 3 years, if I keep her out too long, she can get stressed and that's a way she shows it.
Check humidity, don't handle for too long, especially if you hear wheezing, and see if he makes the noise on his own in the tank.
Please let us know about humidity and length of handling and how often (hopefully not more than 1 session a day 3-5 days a week).