Just a thought.... that black background is still in RGB. I haven't converted it to CMYK yet. Could that cause the issue?
Edit: It was actually in Greyscale.
Grayscale image? How does it look in ID with Overprint preview turned on?
Ugh. That's what it was. I converted it to CMYK and it lightened up a LITTLE but not nearly as drastic as the image above shows. I can deal with this now. Should have converted to CMYK in the first place off the bat.