Submissive behavior?

I just got my first two ratties yesterday. A big boy and a little girl. Both are fixed. When I go to pet them he presses his self flat on the ground and closes one eye (closest to me). She generally falls to one side and sticks one back foot and one front foot up in the air.
I can't tell if they're doing it because they are scared. Or what.... Any ideas?....

If they were scared, they would run and hide. Sounds like these two are total loves!!!

Oh good!

oh my that's awesome! you've got yourself some really sweet rats who love to be loved on, it seems