Bukkit

What steps will reproduce the problem?
1. Plant nether warts in the nether world.
2. Leave the nether world for several hours.
3. Return to the nether world.

What is the expected output? What do you see instead?
I expected all of the nether warts to be fully grown. Instead, they all consistently grew to the 2nd largest size only.

What version of the product are you using?
Release Build 1.06 for CB 1.2.3-R0.2

Do you have an error log of what happened?
No.

Please provide any additional information below.
The server is running CraftBukkit 1.2.4. A plugin that may be relevant is Multiverse, running several worlds each with their own nether world and end world. Also, the plants will continue to grow to their largest size while the chunk is loaded (standing near the nether wart farm).