Irritated eye?

I noticed my kittens eye lining looked a bit red. The third eyelid also looks a bit red. I don't see anything in the eye, it just looks red around it. I'm guessing she just irritated it while playing with her brother. I probably will be taking her to the vet soon because they both need new shots. I noticed it this morning but hasn't changed much since then. I'm a big worrier, so I just wanted to know if I should be concerned about this. 

She squints sometimes but she can open the eye completely. Also, it is her right eye.

Keep an eye on it (no pun intended). It could be the beginnings of a bacterial infection or a flare up of a virus - either way the vet can prescribe drops and/or ointment that will easily fix it. If it looks better tomorrow it is likely just irritation.