I used WLP029 last year in a kolsch and it gave off a lot of sulphur/rotton egg kinda smell, however, I just brewed a batch a couple of days ago with this same yeast and am not getting any of those same aromas. The smell from the airlock is really clean and just CO2 and some hop aroma. I used a stir plate and had a fresh vial. Is this a sign of a healthier fermentation?