In heat, or potential health issue?

I just had a brief moment of panic, but I think I managed to research myself out of an overreaction to a normal biological function. Even still, I just wanted to make sure I don't need to rush Margaret to the vet.

I noticed this evening that Margaret's vagina seemed a little more open than usual. Her genital area seems slightly damp and I found a small spot of a milky-coloured fluid on her liner (I blotted it with a paper towel and it's definitely white-ish clear and has no green or yellow...

In heat, or potential health issue?