When I finished the Captain Sanders chain and looted the chest, I was only able to get two of the four items due to lack of inventory space. I don't know if this is a bug, but it really should instead tell me I don't have enough bag space, instead of only giving me half the rewards.
I went into the Slaughtered Lamb in the Mage's Quarter of Stormwind, where a Master Shadowweave Tailor trainer is, and I was able to learn to make a Pink Mageweave Shirt for free, despite having less than 75 tailoring.