I wouldn't be surprised about this behavior considering the seller is from New York 😉
i am sure he will respond, just look at his feedback rating. sellers do sometimes take a long time to respond. Whatever you do, don't leave negative feedback (at least not for a long time). Doing so, if he feels he hasn't been given enough time to respond to you, could only anger him and if already with negative feedback he may have nothing to lose by not sending you the item at all.