Unload times are not defined by volume, your org chart tells you what time your unload will be. You could have 2 B stores one unloading at 6 and the other at 7:30 so although your volume didn't go up your org chart most likely did
I don't know if it's the same from AE2014 but these are the org chart values for 2015
1 Less than $23.5M 7:30am
2 $23.5M - $28.6M 6:00am
3 $28.6M - $35.7M 6:00am
4 $35.7M - $50M 4:00am
5 $50M – $61.2M O/N
6 $61.2M - $76.5M O/N
7 Greater than $76.5M O/N
I'm not sure if I can post this so...
I found it on store view under active projects
The first sentence was: "Because your store is changing org charts for 2015..." So if you can't find it probably means your store is not changing org charts