Out of the blue today - my cat came into the bathroom and was purring heavily ?

Maybe she was just happy. She's probably just showing affection towards you lol. My cat randomly just comes to me an purr loudly and rub herself against me sometimes. She does it a lot to my mom when my mom is sick. (My mom's asthma acts up sometimes) So she would stick around my mom because she knows she's not well. Cat's have ways of knowing when we're sad, or when we're sick. So if you aren't sick or sad, then she's just happy to be around you. Or she's spoiled! (Which is the case for my cat) lol :)