What time of the day does she fuss? It could be that she is overtired, or that the milk is not flowing fast enough and she is getting frustrated.
It could be a developmental phase when she is just a bit fussy in general, which should pass soon if this is what is happening.
Has AF returned recently? The hormones can affect the taste of the milk, so this could also be a reason that she is fussy. Also - have you changed your diet or anything else about your usual routine? This is something else that could be affecting her behaviour.
Have you called the ABA? They could probably offer you some more suggestions.