I've been checking shelf life of organic ferts myself as I use them spring to autumn then sit on them for five months. From what I've read is that most manufacturers have a suggested shelf life from 6 mo to a year as long as it is kept dry and cool, but if it is a slow release fertilizer how much could it break down in such a short time. Then only organic fert I have had a problem with blood meal from last season but only because it got moist and clumpy. Maybe there is a Phd online that can say for sure, hope this helps.
thnx alot man...i went ahead and used it anyway...i mean whats the harm right, it looked perfectly fine