I've have had two brews come out tasting kind of like what you are describing, except both used different yeast. The first one was a dry yeast made with a Red Ale Kit from Brewer's Best.
You can read more about it here if you want. Review of Brewer's Best Red Ale Kit
Then I brewed up a Bavarian Hefeweizen which is much like a Bavarian Wheat and it came out very similar to my red ale and similar to what you are talking about.
Both of my beers had that banana smell and had a citrus taste and kind of a yeasty after taste. By no means perfect, but totally drinkable.
I would say if the "sour" taste isn't gut wrenching it is probably associated with the style and therefore your particular yeast. However there are so many factors that go into how brew tastes that it could be something completely different as well.