What's with the sweater?

Ok - so bowling tonight...I essentially sucked but that was not the highlight of my evening. Here is my story...I wonder if I'm overthinking it, probably am but its an interesting tale. Let me share.

So there is this guy who always...I mean ALWAYS wears a zip up sweater to bowl. Tonight I nearly took my shirt off I was so hot (relax I was wearing a tank top underneath). So anyways, the guy always wears a black sweater...I have bowled in the same league since October, curiousity got the better of me, I had to ask. Here goes the conversation.

Me: Hey, I have a question for you.
Man in the sweater: Ok
Me: I've wondered this for a while. Why do you always wear a sweater when you bowl?
Man in the sweater: I dont know.
Me: Aren't you hot?
Man in the sweater: I dont know.
Me: Uh, ok
Man in the sweater: OK
Me: Thanks
Man in the sweater: Wow, I didnt even think you'd notice.
Me: (speechless)
Man in the sweater: (walks back to his table)

Ok - now wtf is that supposed to mean. "I didn't even think you'd notice" That was by far the most awkward conversation I have had in a while. So here are some things that the comment could mean.

a) He thinks he's invisible.
b) He thinks the sweater is invisible.
c) He thinks I'm too involved with bowling to notice little things like that.
d) He thinks I'm too involved with myself to notice him.

Thats really all I could think of. I just thought it was ODD.

Thats is all.