It actually does if you complete the second part, it's a 2 part quest. Once you head to Brill and hand it in, a second quest appears at Calvin Montague near the gate. If you go back to the gate he has a new quest for you. So, this is not a bug.

First quest
Follow up quest

There are two quests called "A Rogue's Deal".
https://classic.wowhead.com/quest=8/a-rogues-deal
https://classic.wowhead.com/quest=590/a-rogues-deal

Maybe you finished the first and now the second is shown as available. You may want to talk to the npc "Calvin Montague" again and see if the second is available.

I went back and didn't have another quest to pick up... :(

I went back and didn't have another quest to pick up... :(

I had the same thing happen yesterday, it takes some time for him to show you the quest if someone else has just completed it. Check back later. It was confusing to me too, but I guarantee you, there's going to be a quest.

Awesome, okay. That makes sense, someone was there when I checked. Sorry for opening a non-issue. Thanks!