I agree with the notion that there was a small but urgent demand for pennies earlier in 1860, so the 1860/59s were minted in a hurry and issued - maybe, as Mike suggests - only to a few banks.
I've said more than once before, and no doubt I'll have to say it again, the bronze issue for 1860 was VERY LATE. Why do I say this? Because the mintage, for a completely new issue, is way below what it should have been to replace copper pennies. Look at the huge mintages for 1861/62/63 - you'd expect something similar for the first year too, but not so. The 1860/59 copper s no doubt met an urgent need that may have been relatively small, but clearly there. I simply cannot believe there was never an intention to strike those coppers for circulation.