Not Enough Yeast?

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?

If it was an 11g bag and you rehydrated you should probably be okay as there is a lot more viable yeast in those packs than a typical smack pack or vial but to be sure you can visit:

http://www.yeastcalc.com, plug in the numbers for your beer and yeast and see what the recommended pitch rate was and make the adjustment if necessary.

IMO, if it is already fermenting nicely then you should be fine, just keep it in mind for next batch.

Thats good to hear. I wasn't too thrilled with idea of opening it up right now. I'll be sure to use that calculator on the next batch. Thanks!

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.