Whew that it was only the once, then! As others said, it might be something else coloring her urine, such as food coloring! I hear that Red Velvet cupcakes can be notorious for "AUGH BLOOD!" moments, for instance.

Did you manage to drag her to pee in a cup and get it cultured today? O:> If not... Lots of water to drink, and go pee in a cup Tuesday. Better to rule out a UTI than to risk that it's gone silent, if financially possible.

Good luck!