i would think Gus killed Victor more-so because he wanted to show he was, to quote Sam Jackson, a bad motherfucker. When Mike the Cleaner was on the phone with Gus, he didnt really mention anything about people seeing Victor at Gale's house after the murder. And If I remember correctly, Mike seemed pretty startled when Gus slit Victor's neck. I think if he had informed Gus that he was seen after Gale's murder, it wouldn't have came as much of a surprise to him.
Anyhow, great premiere. Looking forward to this season.