Women get “morning bean” too.
Just like men experience nocturnal penile tumescence (morning wood) during REM sleep from increased blood flow, women have nocturnal clitoral tumescence. The clitoris swells, becomes more sensitive, and natural lubrication can appear, all without erotic dreams or conscious arousal.
It’s a normal way the body “exercises” genital blood vessels. Most women barely notice it because it’s far less obvious than a full erection. Same mechanism, different expression.