Leaving Booz Allen soon, but will come back after 1 year...what happens to 401(k)?

I've been with Booz Allen for 5 years now. I'm burnt out on the defense contracting industry and seeking employment in a completely different industry. I tried finding new positiongs within the firm, but the Career Mobility team is a joke! I've send my resume to hiring managers all over the DC metro area and told them that I want to try new things even if it means applying to Level 1 positions (I am at Level 2 right now).

In terms of our 401K account, I am currently 80% vested. Of course I would prefer being 100% vested before jumping ship, but I can no longer stand the work/projects that I do and have been doing for several years.

My question is if/when I come back to Booz Allen in a year or 2, then do I end up staring all over with the 401K (i.e. having to put in another 6 years to become 100% vested) or can I resume at my 80%? I would ask HR this question, but I don't want 'red flags' to go up if I ask HR and HR informs management.