That's really weird, as every Apple laptop (~6 or so) I've had has the exact same smell, to the point I thought they were scenting them prior to shipment.
I remember that; I seem to recall it being eventually tracked down to a run of keyboards coming from a particular manufacturer that was using bad rubber. I was working at a Mac repair shop at the time, and before they sorted this out, we'd have to give all the replacement keyboards a "smell test" before using them or sending them back as bad parts.
https://discussions.apple.com/thread/207887