can rocking cause shaken baby syndrome

I’ve never been rough with my baby but I just read an article that said even mild shaking can harm a baby. Sometimes to help my daughter sleep I’ll lay her in my arms, one arm supporting her body and the other wrapped around her and supporting her head and I’ll rock back and forth pretty quickly. would this hurt her? I’ve not done it often, only a few times, but would that movement cause shaken baby? I also thought it was only caused when ever the baby is shaken and the head is not supported? I wish I would’ve saved the link to post here too but it was on facebook and now I can’t find it. Please don’t be rude, but more information on SBS would be appreciated.