Wine yeasts tend to throw a lot of esters in beer wort in my experience. It is very likely the 71B that is the culprit. If you don't want esters, you're better off using a clean ale yeast for a beer like this, although if you give this beer a little age you may find them come into balance nicely. I brewed a saison with Gewurztraminer must a few years back using Belle Saison, which has a tendency to throw some banana esters. After a month or two of aging the beer turned out phenomenal.