After Sandstorm and Firestar decide to go on the SkyClan quest together:

With Sandstorm close by his side, [Firestar] padded back across the grass to the roots of the tree where Graystripe and Cinderpelt waited.
"Sandstorm is coming with me," he announced.
Neither Graystripe nor Cinderpelt looked surprised.

Hehe, I just thought the fact that they pointed that out was funny.

From Firestar's Quest