what's with the strangers talking to me?

last night i left work at about 7:30. my metro ride is usually standing up, struggling to keep balance and read a book at the same time. so last night i was pleasantly surprised when i got a seat on the metro at metro center. i sat down and pulled my book out of my bag, flipped to the book-marked page and got comfortable. at the next stop, a guy got on the train and sat down beside me. he was about my age, wearing a white hat with something on it (i didn't get the chance to actually inspect the hat, i didn't want to stare at him or anything). the second he sits down the following happened:
him: you're starting chapter two, huh?
me: yeah.
him: is that grisham?
me: yeah.
him: is that the bretheren?
me: yeah.
him: oh that one's pretty good.
me: good.
him: in chapter X this happens, in chapter Y this happens, then in chapter Z this happens.
me: (internally) please stop talking to me. i don't know about what happens in chapters x, y, z, that's sort of the purpose of me reading the book.
him: and then at the en-
me: please don't tell me what happens at the end
him: well i've already told you what happens in chapters x, y, z...
me: yeah well the purpose of me reading the book is to entertain myself while i'm on the metro and i'd rather read the book first before finding out what happens at the end

and he proceeds to talk to me all the way to my stop. he asked me whether i thought global warming was true or made up, whether i thought AIDS was a real virus or a bio-terrorism thing, and so on and so forth. people were all staring at us. my only hope is that they knew that i didn't want to be talking to this weirdo. but i think people would've suspected we were friends by the way he was talking to me.

by the time we got to my stop i felt like i had done my civic duty by talking to this person as long as i talked to him and i said "this is me" and started getting up. at first i was a little scared that he might get off at the same stop as me and follow me home. i had already thought of multiple escape routes in the event that he did follow me off the train. but, thankfully, he stayed on the train and i was able to walk home in silence, thinking about telling this story in the future and laughing to myself about how f'n weird that guy was.