THOUGHTS ON READING: How involved do you get with the characters in the books you read?

I remember as a kid that I would fly through books like crazy. At least 5 or more chapter books a week if I recall correctly. I become well acquainted with the local librarian. :)  Things have changed as I have gotten older. I now take my time and prefer to relish the experience and allow myself to truly enjoy the book. An interesting plot was my main concern as a kid.

But I've also noticed something else as I've gotten older and that is the tendency to get gut-wrenchingly involved with some of the characters I read about. These are the books I have the hardest time putting down.  I get so involved I get nervous for the character when I know something bad is coming up.  Sometimes I wonder if this is excessive, I mean these characters feel real but they aren't, right? 

Right now, I'm reading Jennifer Nielsen's The Runaway King and I'm dying because I can't go home right this minute and finish reading it. (If you haven't read this series yet, I highly, highly recommend it!) Jaron/Sage is one of my all time characters and he really has a strong tendency to get himself in major trouble and while I know he'll get out of it (this is only book two after all, can't have a book three without the narrator/main character), I'm still really nervous. I feel silly feeling this way since it's 'just a book.' But I can't seem to help it. Some books just really get to me like this, usually ones in which I get really emotionally attached to the characters.  Plots are important to me but characters now dominate my choice of books.  If the character(s) don't interest me or I don't like them I usually won't finish the book.

I just wanted to know if this sort of thing happens to anyone else?  Or am I just weird? Also, what do you think about the change from plot-centered to character-centered reading? Do you think that happens to most people as they get older? I'd love to hear your thoughts. Thanks!