Not at all. Everyone has their own preferences when it comes to what they find attractive.
I think the impression that liking larger women is weird stems from what media tells us we should find attractive. A lot of people buy into these ideas and when other people don't, they treat that person as different (i.e. some guys may tease their friends for dating a "fat girl") and this kind of behaviour often leads to people hiding their preferences if they aren't "mainstream".
That being said, you certainly aren't alone. A lot of guys like chubby girls.
Personally, as far as weight is concerned, I don't have a preference as long as the person is relatively healthy and active, and willing and able to share in the things that I enjoy (i.e. going on walks, bike rides, or other active and fun things).