probably too much light over 24 hours relative to temp/RH/CO2 or too dry. plant looks healthy otherwise.
45 is fine. might have a bit high vpd in mid 70s F, but nothing catastrophic. a little less concentrated fertilier to match an elevated vpd will mostly mititgate it.
If that's coco, it looks a bit dry. only wait for that top layer to start changing color before re-irrigating and make sure you get entire volume wet.. if coco coir / soiless, you also want 10% runoff to maintain a consistent equilibrium (ph and nute concentration) in substrate.