Can a bouncer cause shaken baby syndrome?

We have a bouncer and I bounce him a lot. He's pretty spoiled by it. My mom says I'm bouncing him too hard, but he seems to only like only being noticeable bounced, not a little. His head bobs around a little, but not obsessively. She said she was holding him and he wobbled his head around and it was because I bounce him too hard. Can that really cause shaken baby syndrome? Now I'm worried, I never thought about that. Am I doing something wrong or is this ok?