I started a Mad Elf clone yesterday. It's a higher gravity beer, an OG of 1.090. I pitched a packet of Safbrew T-58 (my homebrew store was out of the liquid yeast I wanted) and it is fermenting just fine. However, I've been reading that under pitching can cause off flavors. Would it beneficial to get another bag of yeast and add it now? Or should I just leave it alone since its fermenting well and not risk contamination?
Safbrew is a pretty hardy yeast, you should be fine. When in doubt, you can always throw another 11g packet in there if you don't want to rehydrate. Since I have gone dry, yeast that is, I haven't gone back.