Is she drinking more? I hate being alarmist but am paranoid. If she were mine, I think I would nip her down the vets for a once over just in case she's brewing pyometra.
Or you might be able to ring for advice?
She's probably just being fussy, but I would check.
Failing that, let her miss a few meals. bowl down for 10 mins, then remove it til the next mealtime NO alternatives of titbits in between.
She'll soon learn if it is fussiness
