Corn snake feeding questions

1 male and 1 female adult corn snake brought out of brumation 2-16-13. They are housed in separate tanks and fed in separate tanks. Females first shed was 2-21-13 and the males first shed was 3-2-13. Both snakes were feeding fine from 2-17-13 to 3-9-13 on frozen-thawed mice. On 3-16-13 female ate, male did not. March 23, 2013 to April 7 2013 both snakes would not eat. Also tried live pinkie mice on 4-7-2013, they showed no interest. Today the male ate, only after braining the frozen-thawed mouse. The female would not eat even after braining, she made a quick hiss as I was dangling it above her head. She does not seem interested. Last year they both had a strong feeding response. Wondering why this might be happening or how long until it becomes a problem. Thank you for your thoughts.