[1.7] Is that a bug?

I have a TE class with this method:

@Override
public void updateEntity() {
	if (worldObj.isRemote)
		return;
	Vector<EntityPlayer> lis = new Vector<EntityPlayer>();
	for (World w : MinecraftServer.getServer().worldServers)
		for (Object o : w.playerEntities) {
			EntityPlayer p = (EntityPlayer) o;
			lis.add(p);
		}
	for (EntityPlayer player : lis) {
		if (new Random().nextInt(5) == 2) {
			EntityItem ei = new EntityItem(worldObj, player.posX,
					player.posY, player.posZ, Mod.foodList.get(5));
			worldObj.spawnEntityInWorld(ei);
			System.out.println("num: " + ei.getEntityItem().stackSize);
		}
	}
}

the foodList is initialized in postInit(FMLPostInitializationEvent event):

foodList = new Vector<ItemStack>();
Iterator<Item> f = GameData.getItemRegistry().iterator();
while (f.hasNext()) {
Item i = f.next();
if (i instanceof ItemFood) {
	ItemFood item = (ItemFood) i;
	if (i.getHasSubtypes()) {
		i.getSubItems(i, null, foodList);
	} else
		foodList.add(new ItemStack(i));
}
}

the output:

[16:59:22] [server thread/INFO]: Player579 joined the game
[16:59:23] [server thread/INFO] [sTDOUT]: [mrriegel.cwacom.tile.TileTerminal:updateEntity:93]: num: 1
[16:59:23] [server thread/INFO] [sTDOUT]: [mrriegel.cwacom.tile.TileTerminal:updateEntity:93]: num: 1
[16:59:23] [server thread/INFO] [sTDOUT]: [mrriegel.cwacom.tile.TileTerminal:updateEntity:93]: num: 1
[16:59:24] [server thread/INFO] [sTDOUT]: [mrriegel.cwacom.tile.TileTerminal:updateEntity:93]: num: 1
[16:59:24] [server thread/INFO] [sTDOUT]: [mrriegel.cwacom.tile.TileTerminal:updateEntity:93]: num: 1
[16:59:24] [server thread/INFO] [sTDOUT]: [mrriegel.cwacom.tile.TileTerminal:updateEntity:93]: num: 1
[16:59:24] [server thread/INFO] [sTDOUT]: [mrriegel.cwacom.tile.TileTerminal:updateEntity:93]: num: 2
[16:59:24] [server thread/INFO] [sTDOUT]: [mrriegel.cwacom.tile.TileTerminal:updateEntity:93]: num: 2
[16:59:24] [server thread/INFO] [sTDOUT]: [mrriegel.cwacom.tile.TileTerminal:updateEntity:93]: num: 2
[16:59:25] [server thread/INFO] [sTDOUT]: [mrriegel.cwacom.tile.TileTerminal:updateEntity:93]: num: 16
[16:59:25] [server thread/INFO] [sTDOUT]: [mrriegel.cwacom.tile.TileTerminal:updateEntity:93]: num: 16
[16:59:25] [server thread/INFO] [sTDOUT]: [mrriegel.cwacom.tile.TileTerminal:updateEntity:93]: num: 64
[16:59:25] [server thread/INFO] [sTDOUT]: [mrriegel.cwacom.tile.TileTerminal:updateEntity:93]: num: 64
[16:59:26] [server thread/INFO] [sTDOUT]: [mrriegel.cwacom.tile.TileTerminal:updateEntity:93]: num: 0
[16:59:27] [server thread/INFO] [sTDOUT]: [mrriegel.cwacom.tile.TileTerminal:updateEntity:93]: num: 0
[16:59:27] [server thread/INFO] [sTDOUT]: [mrriegel.cwacom.tile.TileTerminal:updateEntity:93]: num: 0
[16:59:27] [server thread/INFO] [sTDOUT]: [mrriegel.cwacom.tile.TileTerminal:updateEntity:93]: num: 0
[16:59:27] [server thread/INFO] [sTDOUT]: [mrriegel.cwacom.tile.TileTerminal:updateEntity:93]: num: 0

then the 0 is repeating.

sometimes it starts with 0 or jump from 1 to 0.

when I replace "Mod.foodList.get(5)" with e.g. "new ItemStack(Items.golden_apple)" everything is fine and the stacksize is 1

So, whats wrong?