"It was 4:15 on a Friday and I did not know that this branch closed at 4 on Fridays, which does not make sense to begin with."

You're right; it doesn't make sense, especially considering many banks stay open later hours on Fridays.

But, they were closed. It's not like you got there at 3:59 p.m. or 4:01 p.m., times with a little gray area for actuality. You got there a full fifteen minutes after they were closed. (Banks will also post their hours on the front door. Did you happen to notice those posted hours?)

I don't think "age" is the issue.