I feel like how aware Saitama is of his surroundings is hard to peg. There's definitely a vibe he has supernatural awareness at times-- when he punched that meteor there were, miraculously, no casualities, just massive property damage. He also dodges the sword strikes of Flashy Flash and Sonic, which sort of implies they could have hurt him, but he also took no damage from Nyan Nyan (spelling?) and that cat sliced buildings up. Then there is how he blows up monsters but merely knocks out people, but it is implied he can't help but do both.

Also, Tornado spends a whole fight throwing him around, but when she specifically decides to throw him into space, without announcing it, and suddenly Saitama makes himself too heavy to lift, and he doesn't seem to be doing it deliberately. So I'm not actually sure you can catch him off guard when it counts.