NTA but let me state the way OP said it is not super desirable but not enough to be deemed asshole. First, comparing someone to Ariana Grande could be interpreted as both negative and positive depending on the person. I wouldn't mind if some dudes see me at the gym and say hey Ryan Gosling, but yeah, gotta bear in mind that not everyone likes to be compared to other people for they may internalize it with a more negative impact than positive. Second, it's super common where I live to ask people how many sets you've got left, just much easier to help plan the routine. All and all, in this case, the girl may have interpreted OP's attempt as being codescending or flirty depending on her interpretations. Gotta choose your words better next time buddy.