Do you think the specificity of Hector's derision was written into the script for no reason?
It probably dawned on him that there might be some ulterior motive to Jesse demanding he come to the hospital, however he didn't necessarily think there was something amiss with his car, he might have been looking out from the garage mulling things over (the thousand yard stare is common among thinkers, perhaps the scene was also there to highlight Walt's paranoia of Gus' pervasive awareness), and then turned back to go question Jesse.
We'll have to wait to find out. The way it is written is masterful, mysteries are created to draw viewers to ruminate on the details and what they might mean. I think the whole story is supposed to be surreal, suggesting the sort of paranoia and detachment from reality that meth tweakers live in the midst of.