My Ani was spayed last year, in the summer I believe.
She was fine before and after her spay but started with the lunging (and biting!) soon after I bonded her to Bo my neutered Rex male.
Ani lunges, growls and is one little furry ball of additude it seems.
Her aggression is mostly about protecting Bo from the other pets (who he's friends with, he's such a friendly guy), but she also does this when it's time to be fed, and it almost only happends in their pen.
Ani is just over a year old, and is a rescue.
So far she has only bitten me once (My first bunny bite), but I find not letting her get to me or let her know I am scared, plus useing dominace seems to put her in place, though we are still working on this.
If she's bad I will put my hand on her head and push her down and say "No". I will also then turn my back to her (like rabbits do) and ignore her, and/or play with Bo. Sometimes i will pick her up and cuddle her, just trying to calm her down but let her know i'm in charge.
I'm not sure if she is jellouse of Bo or not as he's a real suck for love bunny, and before he came around it was pretty much just Ani and I and she lived in my spare room (before she ate a hole in my bed).
Anyways, my advice would be to try some of these dominace tecniques, she may be just trying to be the boss and needs to know where she fits in.
Hoepfully she will just grow out of it (That's what I'm hoping with my Ani).