That is certainly a concern. Just be more careful turning left. My rear wheel shaft seal failed at 300 miles, so I speak from experience! Seriously though, if it's leaking enough to get onto the back tire, you should fix it.
In my experience, once you let one minor leak go, it's easier to stomach additonal ones. I have a little different attitude than most since I commute every day and have too much other stuff going on right now. My bike is a tool, and as long as the minor leaks do not affect functionality, I will get to them when I have time. I have replaced my shift lever seal, but it started leaking again. I think oil is coming out of the stator wire opening now. It's not even one drip per day, so not such a big deal at this point.