I think I answered my own question. I found this after a little vigorous Google searching:
"When a compressor pumps one "CFM" (cubic foot per minute), that means the intake port inhales one cubic foot of "free air" (air at atmospheric pressure, which is 0 psig) per minute. (Note: A CFM does not mean in any sense the compressed volume.) So the unit really measures the mass of air flowing per minute, not volume per minute, since a cubic foot of free air is a unit of mass. Some people labor under a stubborn misundertanding that these units refer to the flow of compressed volume (as opposed to free air volume), but this is flatly wrong. The confusion arises because the term "cubic foot" sounds like a measure of volume, when in fact this term in this context is an abbreviation for "the mass of a cubic foot of atmospheric air", which is a measure of mass."
I'm inclined to believe this, because everything you read on the internet is true, right?
I'll go with this answer unless I hear differently from anyone. Hopefully me asking the question will be helpful to someone down the road.