As Trillian said, there is an increased risk of it happening again, but it's not a given. I had a retained placenta and PPH with my 2nd, my third was complication free but my 3rd had a large secondary PPH. ?They will probably be watching you and may even have IV synto ready to go JIC.

Before you had your PPH did you have any symptoms? I had a back pain and pain in my bum that I felt wasn't right. I wasn't experiencing much external loss because the clots had blocked the cervix. I also felt like I wasn't in my head and very shivery if that makes sense for a while before they discovered the PPH.

If you can remember any thing strange before it happened, then speak up if you notice it happening again. I think mine was more severe because I felt silly complaining. If I'd said something earlier they may have investigated and I wouldn't have gone through as much trauma having it controlled IYKWIM.