Why did i just black out?

The oddest thing just happened. It was about 4:45 in the afternoon, and i had just awakened from a nap. I got up, and was walking over to the bathroom. As i passed a table, I'm not really sure what happened, it felt like i had just fallen asleep while standing up. When i "woke up" from that i had found i had accidently spilled over a cup of soda.While i was out, all i can remember was the feeling of many people pushing me. I don't want to blow this out of proportion, but i would really like to know if this is normal, of if it is serious. Thanks for your helps!