Maybe she has another UTI, if she hasn't had any accidents before these three and she's a year old, she didn't bark to go out, she's old enough to hold it.....my dog had bladder stones due to UTI's that I didn't know she had. I'd keep an eye on it if she has more accidents I'd have her checked for infection again,UTI's can be reacuring.
I'm thinking UTI.
Really unusual for an otherwise clean dog to soil their crate. Is she exhibiting any of the other signs of a UTI, perhaps those that she showed before when she had it? Difficulty in urination when you can monitor her?
The last time I found she had some problems was that she licked her vulva after morning pee. After a few round of antibiotics, there were still some crystals in the urinary I collected. As a result, the vet ran a culture urinalysis and a x-ray (I had a discussion before, as Melissa said there would always be some crystals from free catch urinary), but both test were all clean. Honestly, I don't think that she had UTI after the culture and x-ray clean... But I didn't ask too much and she seemed OK by then so that was it.
This time, I don't see any licking or having difficulty peeing... That's why I was more surprised. Is it more like she pee herself while sleeping/without knowing it...
Anyway, it is holiday time and I have more time monitoring her without changing any water intake or else... If it keeps happening, I will need to discuss with the vet again.
There is a condition common in spayed female dogs where they leak often when sleeping. Our doberman has it and takes a hormone pill (perscription) that controls it.