Spotting?

Weird.  Had some spotting yesterday, I assumed that I had started my period....  Now nothing....  Just that one trip to the bathroom. This has never happened before.  My period is due to start today.  Haven't seen it yet. Took a PG test (dollar store) and it was negative yesterday.  I guess it is not that strange that I didn't get my period this morning, but very weird that I had spotting.  Any thoughts?