At the risk of being offensive (and I'm always ready to risk that :-)) I bet you are too influenced by your friends observation and have become obsessive, but have fun, thats what this is all about. Been there, done that!
I second Newbee...this sounds ever so unlikley. It is not unusual to notice new things about a recording even after having heard it many times before...it does not always mean there is a problem/fault somewhere just you listened in a different way with a different form of concetration....but like a red spaghetti sauce spot on your shirt after lunch - the more you look at it the bigger or more obtrusive one thinks it is ( others may not even notice ) - out out dammned spot!
Once you notice something and know exactly how to listen for it, naturally you notice it more often. (Probably not what you want to hear - apologies if this sounds trite)

