Before anything else, I want to mention that my field is mathematics. Recently, I had an interview for a Ph.D. program for a research group that consists of two fields, say X and Y. On the application, I indicated to work in the field of X. However, in my statement of purpose, I mentioned that recently I also got interested in the field of Y, though I don't have much experience in that field so far.
Due to the structure of the program, I have some time to pick an advisor in the program (slightly more than a semester). When I got asked whether I would like to do some more exploration before committing to a project, I mentioned that the program requires me to take courses on field Y in the first semester, and as I am interested in that field, I would like first to see whether I would like to switch my studies to the field of Y. There were only two professors on the interview, both were on the field X, so I am wondering if this can be seen as a potential red-flag that I am unfocused.