saul did not reveal to walt/jesse the extent of his relationship with Gus, which in turn means Mike's relationship.
clearly the cousins were related to Tuco and his uncle, and I believe they were the ones who were supposed to pick up tuco,uncle,walt, and jesse when tuco evaded the dea last season.
what was new was Gus' relationship with the cousins/mexican mafia/cartel, revealed via the instantaneous power of a simple text of Pollos, the same text Walt got in the first episode which led to the sitdown between him and Gus.
a question is now raised, did Gus know of the cousins plan and their connection to Walt via Tuco? probably not, or else he wouldn't have allowed them to for a lack of a better word, 'wack' Walt if he was to call it off, like he did.
My theory is Gus now knows he has a lot more leverage in negotiating with Walt concerning operations. He may not be so kind in their next sitdown, and may offer less $.
Walt will soon learn of the cousins and their desire to kill him, along with Gus' desire to do business. Walt has a decision to make, and he knows Skylar, Holly,Walt Jr. (formerly Flynn) may be in Gus' crosshairs if Walt declines to work with Gus again.