Strongly foreshadowed that Sansa will make a play somehow here in the future maybe for the North, maybe just against Jon. Canonically she had to time for him and treated him as such. LF is playing right into that.
If you're referring to the look she gave Littlefinger when the houses of the north declared Jon King, I don't think that's true. That look implied to me that Sansa realized Littlefinger would now be a threat to Jon. LF openly admitted that everything he did was to make the picture of him and Sansa on the Iron Throne come true, when everyone still assumed the houses of the north would not follow a
Edited for profanity. Please do not do it again.. Now that they do, Jon has become a roadblock for Littlefinger.
Reminds me of a scene two weeks ago, when Jaime threatened to put Edmure Tully's wife and their baby in a catapult, which most people interpreted as a sign of Jaime's cruelty, when it was obvious this was just part of his scaretactic to end this conflict as quick and peacefully as possible.
However, I think it is possible Tyrion and Sansa could end up on the Iron Throne. After Westerosi law, they're still married, and Dany told Dario she needed a person she could trust in Essos when she sits on the Iron Throne. It is possible that she wins the war and decides life in Westeros isn't what she wants, installs Tyrion as King, and moves back to Essos.