There are rules about when you actually "reside" in another state, set by the states of course, and that will determine if you lived in Florida. (Sometimes there may even be special rules for students, but generally internships are just limited time employment or contracting arrangements.) The fact that Florida does not have individual state income tax might be a factor worth considering when you are asking if you qualified as a resident. If you have a choice under the law, generally we figure things both ways and then make a choice.
But on your federal return, either way you need to report that income. Since you received a 1099, you might report that on Schedule C, and deduct any related business expenses. Alternatively, when there are no related business expenses, people sometimes simply report this as "other income," but Schedule C is typically better because that way it will figure your self-employment taxes and also qualify you for the qualified small business tax credit.
