I got up, went online, found the class schedule and discovered that there is a class at 9am that would be ideal...but I wouldn't be able to have breakfast beforehand (I hate doing yoga on a full stomach and you're not really supposed to anyway). So... anxiety drove me back to the schedule and, upon closer examination, I found a perfect class later this afternoon.
Situation resolved; but doesn't it seem so silly? Normal people don't worry about these things or get upset when they're routine is uprooted.