I would have her checked.
She may have a underlying utering infection. When they go into heat the uterine tissue swells, becomes fluid filled, and engorged with blood. When they go out of heat, sometimes some fluid remains in the uterus or uterine tissue. This is a good place for bacteria to grow.
The infections are most commonly seen when they have had a recent heat.
I do not want to scare you so I am just mentioning this and do think I am saying she has this. She could have a tumor in her uterus that is bleeding as well. It is important to make sure this is not the case too.
So yes, she should be checked.
No, you can not tell with an outward exam. She will have to have bloodwork or at least a microscopic exam on her vaginal drainage.
No, their abdomens do not appear distended or sore to the touch.