"They couldn't exactly plan on Excalibur doing this, could they?" They would be in trouble if the Witches realized how detrimental the Holy Sword was to the city. Clare hadn't met Excalibur so she didn't have the full impact of the sword's... nature. But given right now, she did not ever want to meet this person.

Clare saw past the negative aspect of the statement, "Probably best to be quiet for a little while. A lot of what I said today I didn't realize was there till after I said it." Clare let the silence fill the air a moment before getting an idea... and matching her steps to Kid's so she was a mirror of his motions.

Hard to tell if mocking, or being cute. This being Clare, it might actually be both.