Custom colour item names lose format when repaired in anvil

I created an enchanted diamond axe with a custom name using NBTedit. The custom name tag had '§6Waraxe' which creates an orange item name 'Waraxe'. I then damaged the axe and repaired it in the anvil, however the item's in-game displayed name changed to cyan colour '§6Waraxe.'

I'm not sure, but I also think the unintentional renaming of the item raised the xp cost of repairing the item.