While I agree the stamp is obviously an add on by photoshop or whatever. There is another spoiler, from a long time ago saying that a couple dressed in blue were on a Puerto-Rico - Miami flight on the 18th. That couple can only be **** (see spoiler thread :-). That's why I don't think the 18th is fake. The new-york date is wrong or the whole spoiler is fake. That's my take on this.
As for the Uchenna Puerto-Rico photo being a fake, that would be world class fake (the shadows, the airport, depth) and somebody would have to have access to production stills to get a photo of a TAR cameramen. The Uchenna photo looks way real to me.