My periods are usually heavy, but this time around they are light when normally I have a heavy flow. What could this mean? Should I be worried?

You could just be having an off period. If you're having sex you could be pregnant. You could have a tumor. You could have an infection. You could have a cyst. You could be stressed. You could have gained weight, or lost weight. You could be on medication. The list goes on.

In other words. There's really no way for us to know why this is happening. If this is a concern, than see your doctor.

As noted, normally it is nothing, just a light period, they can vary from time to time.

But there are 100s of reasons for it, and sometimes it happens for no apparent reason