I think you need to not worry about it unless it creates an inconsistency in your application. If one of your essays says, "two years ago when I was a sales manager at XYZ" and your application lists your job as "marketing manager," then you might have an issue because it could create confusion. If the mistake is a minor wording mistake that doesn't substantially change the meaning, then let it go.
Ultimately, AdComs want to know who you are, what you've done, where you want to go, and how you present yourself. If you honestly represent yourself as best you can, no one is going to hold a minor mistake like incorrectly listing an old job title after you're admitted.
Since you've already emailed admissions, I'd just wait and see. If they respond and ask for the correct title, reply honestly. Otherwise, just let it go.