Vibrating rock n' plays... harmful?

Di

Can the vibrations hurt my baby? Sounds silly but I assumed it was a slight vibration on the bum part of it but it vibrates all the way up. Could it be hurting her head/brain? She's just so delicate at 26days! Anyone else have this worry? Of course, it is also a lifesaver since it calms her so well! Ugh! #FTM