After Sonny's gaffe at the drugs meeting, Vito called in Luca Brasi and told him: "I'm a little worried about this Solozzo fellow." What he was worried about was that Sol would make a move against him to force him pr Sonny to reverse his decision not to accept Sol's deal. That wasn't irrational, it was business. Where Vito slipped was in the next sentence: "Go to the Tattaglias, tell them you're not too happy with our family..." as if anyone would believe that Luca would abandon his Don--or that Vito would allow Luca to ply his deadly trade for another family.