Inappropriate peeing

Polly has recently started peeing in inappropriate places. The litter boxes are in the same places as always, litter is the same, feeding is the same too. The only change that we can think of is that she is no longer top kitty, Sass has taken over that role.
Would this be likely to be a reason for her peeing outside the litter boxes? I'm thinking it's most probably a uti but have also considered that it could be the change in kitty dynamics.