Photos losing resolution on export

I'm exporting photos from Lightroom and for one specific session when I export the dimensions are shrinking a toooon. The image is going from 5040x3360 to 2560x1707. I've checked my export settings and they're not set to resize anything. The kicker is it's ONLY the images from this session. I exported photos from a different session earlier in the day and the size didn't change at all. I even exported them at the same time and the one from this session changed size and the other one didn't.