Is it normal i was at the library and a woman told me to get out of...

I was in the library, one I normally don't go to but thought I might as well try it out as I was nearby and I went to the room called "YOUNG ADULTS".

I visit this room in my own library and no one ever questions it. Hell in my own library, there are other 20 somethings in the young adult rooms and being 22, I thought this was perfectly okay because the books I read are in that section most of the time. I never feel like they're too young because in that room, there's a mix of books. Some are definitely more for younger teens while there are many more that seem to be written very similar to any book an adult 18+ would read as those books involve higher vocabulary/writing/involve characters 18+...

Anyway I'm in that room, browsing and then I sit down with a few books and read the first few pages to see if I want to borrow them with my card... I'm there many 5 minutes and there are only 2 other people in there - two teens maybe 13 years old just looking around together.

So this woman in her late 60s comes over to me and whispers, "I don't think this is the right room for you" so I responded, "What do you mean?" and then she said something like, "This is the teen room, it's meant for children in their teens. You might want to leave the room." So I then said, "this is the young adult room, I'm not old" and then I just left because I didn't know what to do.

I put my books back but on my way out, I went to the main desk and asked them what age the young adult room was for and the two women at the desk both sort of said the same thing/told me they both read young adult sometimes and one of them was probably about 55, the other was maybe 40. Then the girl comes up behind them who is maybe 35 if that and said she thought young adult was a range of anywhere from 12-30 something/that the books she reads usually incorporate characters in their 20s as well.

So I'm like
1- what the hell was that woman's problem telling me to leave the room
2- At 22, I'm not an "old adult", am I?

Is this normal? Even if I were 50+, I should be told to leave. We can read what we want and it doesn't say the room is for babies...