"In some cases, notification of selection status will not be available before the beginning of April and in the case of late applications no earlier than 30 days after receipt."
Also, the NASS brochure says April 15th is the latest you should hear back. I'm not sure how exactly those two policies differ.
It could just be that they are still looking over your application, or they might just be delaying making a final call for you. One very likely possiblity, is if you are from a popular area for the Naval Academy (such as the East Coast), they might be waiting to see how many applications they get from less represented areas. Since the Summer Seminar is used largely as a recruiting tool they like to get people interested in the Naval Academy from areas that usually don't show much interested (similar to how other colleges strive for diversity). As a resident of Pennsylvania, I'm betting that's the case for my area, as another applicant from my high school and I haven't heard back, even though we applied in February.
Best of luck, hope you hear soon, and if not then I'd say feel free to give them a call. That's what I plan to do if I don't hear by the end of next week or so.
