Yes, Exodia Contagion has always left a projectile that explodes after a set time. However, the projectile will not explode if you kill an enemy and the projectile goes through the enemy leaving what I call "duds". So be wary of that.
Also U26.1 and still no bloody fix for that cursed 1 sec delay after air swing.
Might as well mention it here too but, Exodia Contagion is unable to fire if you're equipped with a sniper rifle (one with an actual scope) while reloading. (Lanka, Rubico, Komorex, etc...)