Only if they had authorization to take money out of your account instead of just being able to deposit.
Anyone you have ever given a check to also has your account information. Doesn't seem like your ex-employer having it is much of a risk.
I owed a small company and had everyone on direct deposit through a payroll service. The service put my partners bonus check into his sons (jr) account by mistake. I was surprised that they where able to get it back out without anyone having to sign.
On Monday I would call the bank.
This post reminded me that when I was a kid and had my first job (as a 16 year-old), workers were still being paid with cash in a small brown paper envelope every Friday. Included with the small packet of bills and a few coins was a slip of paper with the hours I had worked and a brief calculation to show how my pay was arrived at.
How times change!