I had purchased a pair of '02 mexi blacks at a show in January of this year. They were both pretty docile at the time, no biting, just your typical tail rattling and a bit of posturing. After about 4 months or so, the female started to bite, hungry or no. She actually became quite the little terror, while the male remained fairly docile. Unfortunately about a month after her sudden change she mysteriously disappeared from her enclosure, and has not been seen since. No evidence of her still being around has been found either.
Anyways, I sent an e mail to the breeder, and he said that this seems to be common behaviour for Mexican Blacks, and that they seem to go through 'phases', on top of the normal nastiness that can be attributed to age, sexual maturity, shed cycles or feeding responses. He also said it seems to be a more prevalent trait in females = Figures eh?
GL with her, take advantage of her when she's next in a 'nice' phase, lol.