B.C.
At 38 it's not too soon to start up with some peri-menopause symptoms.
It's just a really gradual long drawn out (can go on for 10 years or longer) reverse puberty and that means hormone fluctuations.
You know for sure you're in it when you get your first hot flash.
Bring it up at your next annual checkup and see what your doctor has to say about it.