So that's why the protection spell felt familiar. Part of Twilight is impressed; protection spells are Shining Armor's special talent, but she had no idea her brother could cast a spell big enough to cover an entire city.

She's not about to let herself stop being mad that easily, though.

"Okay, okay, I get it. You've got a really important job protecting all of Canterlot with a force field only you can conjure up. But still..." Twilight sighs. "How could you not tell me about something as big as your wedding? Am I not that important to you any more?"