No, this was not lagging growth, this was zero growth, period. And I do have chunk grids on in REI's minimap so that's not the case, but even in the worst case there will be some sporadic growth.
There have been reports of other servers running the same customized build of craftbukkit that we are also experiencing this issue; We're looking into it.
Odd, I noticed that melons and pumpkins are growing exceptionally fast since the introduction of 1.3.1