I've heard the same "rule" C-Q. Without causing offence to any members older than myself I think it's a rule from my parents generation. I also know what you mean about more mature women with long hair but my mental image is that the 'creepiness' comes from having long hair that is in bad condition, straggly, split ends, messy etc. Actually, come to think of it, that's a bad look no matter what your age

FWIW I don't think 31 is too old for long hair. I had hair almost to my waist at your age (doesn't that make me sound old ). I wore it up most of the time. I cut it all off while pg and gradually got it really short right before I had DS. Now I'm growing it again and TBH hadn't even thought about the age thing.

I think if you're comfortable, stay as you are. If it bothers you for other reasons, then change it. I wouldn't worry about the age thing. It's more important that long hair is looked after and cared for.