Geek out has been around a while, since the 90s at least I guess, but this is slightly different. For a start, it's used in an impersonal construction; "That geeks me" rather than "I geek out (over/at/...) that". Secondly, it conveys a sense of admiration of someone else's skill through shared knowledge. The original "geek out" sense doesn't have quite that same admiration, it's more a feeling in the person who is geeking, wherease here it is something or someone else that geeks you.