Yes, I think small dogs KNOW they are small and are less accepting of rough treatment. My runt Sheltie is the most demanding of "her" space, my over-sized guy is much more tolerant of bumps and rough-housing.
It's not even really that they are less accepting of rough treatment as an attitude, they are more easily more hurt by kids. They get stepped on, kicked or grabbed at by kids, and it hurts. On the other hand, a little kid can not easily hurt my Labrador, no matter how much he is tugged at and sat upon.