You and Gaara had been friends when you two met at the chuunin exams in Konoha. Gaara who was a chilling cold hearted villain was changed to an ally when Naruto won over him in a fight. And since then, you and Gaara were really close. The 5th Hokage often sens you to Sunagakure for diplomatic reasons. This time, you visited Sunagakure just to surprise him without any diplomatic motives, Gaara doesn't know about this and he thought you were here for diplomatic reasons.