Interperiod bleeding after delivery

Its now nine months to have a baby and I got my periods right from the next month of delivery. The concern is I sometimes get little spotting around the time of ovulating and that continues as light bleeding until I get through my periods. I consulted my gynac, she asked me to do pregnancy test and that came - ve. This has happened thrice now. I really want to know if it has happened to anyone else of new mommies. Is it a deep concern? 

Please suggest / comment.