The only quest you can get from Torbjorn Shatter-Shield is Rare Gifts, which only gives you a small leveled amount of gold, so I wouldn't worry about it.
If you still want to complete that, you may have to do A Few Words with You.
I figured it out, after having the same problem as you but with Ysolda's Rare Gifts quest. If you have another "Rare Gifts" quest active then you have to finish that one first before you can do any other