o continue: I had many problems with upper management, one of which was their wanting me to 'tweak' time sheet accounting so that new entry level minimum wage employees were paid for as little as 75% of their legitimate hours worked.
That's actually a criminal offense (payroll fraud, or something similar) and you should have called your state labor commission and reported them right then and there.
Well two weeks after I left I found out the newbie replacement didn't perform the audit when I accidentally clicked on a bookmark at home (Putty) and I was suddenly in a server from my old job. I logged out and didn't feel particularly compelled to tell them that my keys were still trusted. About a month later I made the same mistake. The hole was no longer there. I thought to myself, "Good for him. I guess he's not so incompetent at all."
But curiousity a la Facebook and Twitter revealed that a server had actually gone down that day. Apparently there was a 'rm -rf' oopsy!!!
I hate to say this, but you could have ended up in jail for this little "oopsy". If for any reason they thought the "rm -rf" wasn't an oopsy, and was malicious, and someone did forensics on the server and determined you had logged on after your termination date, you probably would have had the FBI knocking on your door.
Not only is it the employer's responsibility to shut down access for terminated or resigning employees, it is the employee's responsibility to destroy any company data they might still have. This includes ssh private keys that might give them access to company systems. It's always a good idea to cover your ass, especially when dealing with former employers that are unethical enough to short their own employee paychecks.