This is part of the cutscene before the last fight in the Lair of the Shadow Broker DLC. After you enter the Shadow Broker's room, he will eventually mention the squadmate you brought with Liara.

Note the animation error on Garrus' reaction. This is pretty much why Grunt does nothing aside from looking at Shepard. BioWare could've done something more than slapping an "I'm-readying-ma-gun" thing on everyone.

Aditional information:
Paragon Male Soldier Shepard;
Collector base destroyed;
All members loyal.