It seemed normal and when I looked at my friend's 15" MBP, it looked so small, almost like a 13" MBP!
Same happened when I had to use a 13" MB for a couple of weeks, when I finally got to use my 15" MBP again, it seemed huge!
Haha, yeah, when i go to use my 15", it seems like a toy computer, especially with the lower resolution. But yes, i was very surprised that the 17" wasn't as huge as i had expected. I think because of what you said, when you look at the 17" at the store, next to the 15" and the 13", it looks pretty massive, but when you have it on its own, the size is fine.