We traded our 2011 MKX in that didnt have that noise, for a 2015 MKX, that does.
Been at the dealer for almost 2 weeks now. Hotline has instructed to check valce clearences, which are to spec. They are having a hard time diagnsing the noise, since it goes away after 3-5 minutes and wont likely do it again the same day.
From what i read here, it's supposed to be "normal", but if thats the case, all of them should do it. Something dont jive here. Furthermore, if Ford claims it to be norman (which they havent said), one would think the Hotline would be aware of that.