Glad you're ok!
I would probably not replace my helmet if I had rolled over on it after a crash landing, the way you describe. But only you know how hard the impact was. I would say that if the impact was hard enough that your head would have suffered damage (bruising or lumps, not superficial scratches) - the helmet has also suffered damage.
I don't mean to sound flip or reckless, but I've rock climbed for several decades, and the recommendations about when to replace your gear have swung back and forth. The few real tests that have been done usually show that the gear can take a lot more than the most conservative estimates. I don't hold by the "if you have to ask, you know"-rule of thumb, because I know cautious people who would always ask, and reckless people who would never ask... And for that matter, my life is worth more than the total of my climbing gear, but that doesn't mean it needs replacing 
I have some very nervous nellies for climbing partners, you see.
Winter riding is much less about badassery and much more about bundle-uppery. - malkin
1995 Kona Cinder Cone commuterFrankenbike/Selle Italia SLR Lady Gel Flow
2008 white Nakamura Summit Custom mtb/Terry Falcon X
2000 Schwinn Fastback Comp road bike/Specialized Jett