To now feel awkward around her?

[TinaTeaspoons]

I genuinely thought my colleague was early twenties. Today I found out she was 38. So the same age as me.
I feel really weird over it for some reason and also embarrassed because I have been speaking to her like she is a lot younger too. Aibu to feel like this ? It feels so odd to have assumed she was someone entirely different in a way. She is single with no kids and obviously looks exceptionally young which made me think she was so young.

Do you mean talking to her thinking she was much younger means you were patronising?

Like others have said, if you were in your 30's and someone else was say in their 50's or whatever then of course there would potentially be differences in life experiences but 20's v 30's is bizarre.

I'm so glad for this thread because that woman in the OP could be me. There are countless threads where people say this never happens and nobody looks less than 7 or 8 years of their actual age but that's nonsense.
I am also the same age and people assume I am late teens/up to 24 as the oldest. I do always notice when people assume this. Why? It's all the 'My darling' and 'babe' sort of chat that filters through. Or the 'You're not old enough to remember this yet but....' or 'When you have kids' . They speak in a more big sister/older brother type way because they believe they are older and wiser.
I have had people change towards me as they mistakenly assumed I was a sweet young girl just starting out. Not the mature woman I actually am. It's horrible because you never know if people like you for yourself or whether it's just because they see you as a sweet young girl.

People assume I'm a good 10-15 years younger, I just take the compliment, and carry on.

5/7 years younger is a compliment but nobody wants to be perceived as a young girl when they are almost 40 surely?

No. I am not judging the fact she is single with no kids. Just still very much taken aback.

I wouldn't worry about it! Most people at work think I'm a LOT younger than I am and while I initially found it embarrassing it's now a source of amusement.

When meeting a new colleague he dropped into the conversation, "it's alright for young ones like you- no doubt your parents fund your lifestyle". I've not lived with my parents for over 25 years and they certainly don't fund me in any way shape or form!

It's not amusing though. That's the whole point.

I had this with a new employee. He was tentative and shy, partly because he was from another country and struggled with English. I had him down for mid 20s. Was shocked to find out he was 36 and a father to primary school aged kids.

A young girl is under 8. A woman in her early 20s is not a young girl.

To be fair I always refer to anyone in their mid to late twenties as a young girl.
Yes, she is shy and quiet too which made me assume a lot younger.