No she didn't. But anyway:
I do not mean tell the whole story but let them know of the danger. Besides all Sansa was told was that they were leaving and she went to tell Cersei and Joff goodbye. Later Cersei says she told her everything because she wanted to sound clever and not tell Tyrion that actually Ned had told her what he knew earlier.
Sansa'a actions are only concievable anyway because she had no idea Cersei was an enemy of her family. When she realized that she withdrew into her fortress of courtesy.
Besides, if it was too dangerous to have Sansa there entirely...well she should have been sent home which is what I would have done with both Arya and Sansa after the event at the Trident if I were Ned.
Edited by Valmy, 25 April 2011 - 01:10 PM.