No clue what might have been wrong with your login information. I would not worry. This happened to me with other companies, not Service Sleuth, to my memory, and I usually check to be sure my CAPs lock is not on first. Changing browsers sometimes rectifies the problem. Or sometimes I just shut down my computer and when I power back up, it's fixed.
I've worked with Service Sleuth since 2008 with no problems, Except for their long payment time frame (PayPal approximately 60 days after the last day of the month in which they were shopped, meaning between 60 and 90 days), I like everything else about them. And I can live with the long payment time frame.