I don't know about the cohibas, but the PSD4 are noted for being a cigar that is very good when fresh, and then moves into a "sick" period w/in 6-12 months (?), after which they're pretty hard to smoke for the next year or more. Then they improve considerably and are hard to beat. The time periods vary, I guess depending on storage conditions.

There is a wealth of information over on Cigar Pass.