Hmm... usually that sort of behavior is caused by hormones, but 3 months post-spay that's clearly not the case. Did it start right after the spay or was there a delay before it started? Rabbits can hold a grudge, so if something she found to be traumatic happened on spay day, perhaps she blames you for it because you took her to the vet for the procedure.
One thing that may need to be ruled out is a medical issue. If she has pain somewhere, it could cause her to lash out. Has she had a regular vet check-up since the aggression started? Food-specific aggression strikes me as less likely to be caused by something medical but it's still a possibility. Any changes in appetite, activity level, mannerisms/movement/gait? Are there any spots where she's particularly reluctant to be touched? Sometimes the hints they give about pain can be incredibly subtle because they're hard-wired to hide weakness. For example, my Nala is at the vet having her teeth trimmed today because of spurs on her molars. Normally, if she's in the front part of her cage and you approach/open the door, she'll sit there and wait for you to pick her up (or even run up to you for attention), but in the 2-3 days leading up to a sudden decrease in appetite (which prompted a vet visit last Friday), my husband and I both noticed that she started running to the back corner of the condo where she knows it's very difficult for us to reach her. Something was definitely off/bothering her but we couldn't put our finger on what until she suddenly refused to chew her precious pellets.
Beyond that, I'm not really sure what could be causing the behavior. She's transitioned from juvenile to adult now and should be settling into her "adult" personality but for said personality to take a sudden aggressive turn is very unusual, making me think there was something specific that triggered the change. Thinking back to exactly when it started and what sort of things were going on in her world around that time may help.
