DST from Bench Karma

I am part of the core raid group for my guild and I was away on vacation last week. I didn't sign up in time to make the cut for the raid this week and was numero uno on the bench. I stayed online and played an alt, then I get a message from one of the GL's confirming I still need DST and telling me I'm gunna be subbed into for a quick Gruul's once the TK ends. I was super stoked as we have not been doing many Gruul's these days. We get to Gruul and boom DST drops, Magus-Blade too. I roll 100 and DST is mine; the 100 beat out a 94, 92, and 90.