You probably figure it out by now but since it’s stated as unanswered I’ll share my experience.
I’m Brazilian and I have visited the US for the first time in january (NYC as well). Second time I went there (end of april) I was faced with a bunch of questions like: “Do you know anyone in the US / in NYC?”; “How long do you plan to stay?”; “You have been here in january, what’s the purpose of your return?” amongst other questions and some of them repeated a few times…
In case you have a valid passport and visa, and if you left the country within the time period that you told them you would in the first visit, you should be fine. Just remember that a tourist visa is meant for tourism, and if they find out you are going there with other intentions they might not let you in. So if you tell them (and I am not telling you to lie) that you are going for a course, it could potentially be a problem in case you have a tourist visa.
What I told them when I went for the second time was that I didn’t have enough time to see everything I wanted to see in my first visit, and since I am a graphic designer that I wanted to visit some of the museums I didn’t get to go.
Just be prepared because there should be questions about your early return.
By the way the second time I went there I entered the country through Detroit, but they knew I was going to NYC checking my ticket (or name?) on their system.
Credit:stackoverflow.com‘