Your Secret clearance now expires sometimes within a matter of months of being off a contract or out of a job that requires it. OPM is cleaning up the clearances, and revoking millions of them. I've had employees go from active TS to "eligible" status (which mean no clearance) in a matter of a few weeks after their contract ended. That whole "10 year active period" is not true, at least anymore, unless you are in a position that requires the clearance for that whole period of time.

You're considered lucky to retain a clearance more than a month out of the service now, too. OPM is taking a tough stance on unused clearances and it has negatively impacted the job market for recently separated Veterans because the contracts that come out all require a pre-cleared workforce, which is a rapidly diminishing pool of people to pull from given that clearances are now being revoked as soon as someone gets out of the service or leaves their last position.