Player is launched when jumping from projectile

I think I may have discovered a bug. I have created a bullet that shoots very slowly, if I shoot the bullet into something, and then climb onto the bullet, and jump, I am launched as if the bullet has transferred it’s original momentum (it is now holding still) to the player. Here is a quick GIF to demonstrate:
http://i1285.photobucket.com/albums/a586/jamendx3/Projectile%20Launching%20Player_zpss52yz2g4.gif
As you can see, I am creating clusters of bullets, and when I jump while standing on them, it moves me in the direction that I shot the bullet, I am holding completely still when I jump, but it moves me. Is there a reason this is happening?