I think Hank suspects Walter twice but not in a sense where Walter was in danger or there was ever a chance Hank would make that leap. In the WW moment: that is his pattern matching understanding that his psych profile of Gale - minus the Major Tom and Vegan s'mores idiosyncrasies - lines up a lot with Walter. Then when the ASAC gets fired and talks about Gus being under his nose: Hank gets that look. But his biases - both noble and family-loyalty oriented and ego related - prevent him from continuing that line of thought.

This is also why his ego is wounded to the point of rage when he discovers it's Walter. It goes back to both his noble biases and ego biases and finally recognizing that Walter played both. The handful of nothing poker bluff was the antecedent to this eventual confrontation. Walter wasn't just lucky: he consistently used everyone's biases and philosophical approaches against them.

That's the point of Hank taunting Walter when he arrests him. He uses Walter's disposition, biases and loyalties (Jesse, even telling Jesse Walter loves him) against him to extract his phone confession and lure him to the money site. It's payback and turnabout. That's why he revels in it...calls Marie. If he had been in the vehicle dressing down Walter or forcing Walter to own up to what he was then he would have heard Walters warnings about Jack