Npcs have a simple like or dislike system somehow you got on her dislike list, you must have done something to annoy her like steal or kill in Whiterun maybe. Some quests can change the disposition but i can't think of or find any for Olava.
I've played thousands of hours of Skyrim, and now on my Xbox 1 SE, I got this for the first time. I did have one of those bits of weirdness earlier with the character -- where you could walk through town no problem, but walk into Dragonsreach and EVERYONE is suddenly hostile. I tried several reloads but couldn't clear it. On the last one I walked into the Drunken Huntsman and it happened again. The innkeeper followed me out and into the barracks building. I let him wallop on me a while (it raised my block) before having to kill him. It was in front of guards but they didn't flinch. I ended up having to pickpocket a guard with intent to fail so as to be taken in an absolved of all crimes. Other than that I can't think of ANYTHING I've done that would anger Olava. But I've heard her say that 3 times. Its weird since to me at least it is completely new.