You should be worried, because there is no way to ever be certain this will not come up.

As long as you have no significant gaps in employment post-HS, it was never mentioned on your social media, and previous employers and references know nothing about it then they will probably not find out during the background check.

If they do find out and don't hire you, no big deal, lesson learned for your next interview.

But there are two big problems here...

1. They will likely not complete the background check until AFTER you start ground school. If they find out then, you will be pulled out of class one day, taken to the HR officer, and fired on the spot. You will have to take a cab to the airport and buy a ticket home. You have now been fired by a 121 employer for lying and will probably never work in the business again.

2. They don't find it on the background check but somehow it comes to light years later. End result, see #1. This is unlikely but it will still be hanging over your head...guess it all depends on how well you will sleep at night.

Also...social media is archived by various services. Just because you sanitized facebook yesterday does not mean an old copy of your stuff is not available somewhere.

You probably have to decide whether to even accept this job now, in my opinion doing so would be a significant career risk (depending on how secret you kept your college career). It's too late to go back and be honest with them, and odds are good that they will not complete your background check until you are in ground school.

This should be a wake up call. This industry does not tolerate dishonesty (unless you are a senior manager) and it's really hard to hide anything these days.