Thanks Finnegan. Did some more searching... if it was a swap it looks like the car would throw 2 codes, 1 for each bank...
Here is a thread that is linked the CEL to the MAF!!
http://www.e90post.com/forums/showthread.php?t=682378
More context: on initial start after the install I foolishly did not connect the air pump hose fully, thus a loud vacum noise. But no code was thrown then.