Gmax 1.5 xt + w/ E3D hotend. Nozzle drops temp

So ive had my max for a week or so, and im starting to get things figured out. I recently switched to an E3D hotend, which is great, and I love it. However, during my FIRST ever long print with it (or the stock for that matter) it dropped to 175 on the hotend and just stayed there. Midway during the print I saw it, upped the temp manually and a few dozen layers later it did it again, and never came back up... Of course i found the nozzle had knocked off a piece of filament and the part failed.
What would/could cause a nozzle to just decide to lower itself automatically?
thanks in advance.