Why did the officer think the man should notice the speed limit?

W: Can I see your license and registration please?
M: What is the matter, officer? Did I do something wrong?
W: You were speeding.
M: I was speeding?
W: You certainly were. Do you have any idea how fast you were going?
M: I’m not sure, but I was going about 35.
W: This street is in a 25-mile-per-hour speed zone, you know.
M: It is?
W: In this state, the speed limit in residential areas is 25 unless otherwise posted. (4) Besides, there are signs all along the streets.
M: (5) I’m sorry, officer, I guess I didn’t notice. I was thinking about my job interview. I’m on my way to it right now and I didn’t plan to come this way.
W: What do you mean?
M: Well, I was coming down on Elm Street, but it was congested with traffic. There was some kind of congestion. I’m nervous enough as it is.
W: I’ll just give you a warning this time.