Quick rent question (idk sh*t about law)

So I have a lease the expires at the end of March…. The lease got bought out about two weeks before the end of February. I paid the original landlord for the month of February (their bill was always due at the end of the month). The next landlord tried charging me late fees for the month of March claiming their rent is due first of the month ….

I haven’t even been with them a whole month… is this worth looking into or just pay it and move on? I’m moving out anyway… thanks in advance!