Very light period?

Question

I don't think that we conceived, and my period started when it was supposed to, but aside from one morning when I woke up and wiped (TMI, I know) it's only old blood and light. Should I be worried? Usually I have a medium-heavy flow.

Answer

Are you completely sure you didn't conceive have you tested?  
If you're used to having heavier flows then this sounds like possible ib...?