I'm a big fan of the unconscious processor of thought, an ability where our brains can make connections that we are not consciously aware of but still exist - although it is a model with many flaws it best describes what I try to convey. Gus as posted above was somebody who was constantly vigilant, had meaning for every action every thought every word and every move, he planned and planned everything with backups upon backups, prepared for anything as best you could be. I think when approaching the car, as Miah said, he knew there was a loose end to Jesse's thoughts and that Walt was desperate to bring Gus down.Ever returned home late at night to silence, nothing is out of place but that sense of something isn't right, something has changed. It may not be based in reality but I think Gus must have had some thought cross his mind at the time that told him something was happening and because he didn't know what is was, he avoided the risk that was obvious at the time - his car. He may also have subconsciously noticed Walt watching him since we only actively "see" 5-6% of our vision and consciously process it and when alarm bells starting ringing, he didn't know what it was, but that feeling kicked in.My thoughts on the matter at least. But Gus was my favorite character of the show since he is the one I can best relate to. Business like and adaptable but as soon as business turns sour, the quiet and calm nature is deceiving for something extremely dangerous, especially when the person has immense power and knowledge.