I did similar when I went to a friend's with my serger. Hers wasn't working, so she wanted me to see if I could find the problem. I packed my serger, just in case I wasn't the mechanic that she thought I was. She had a project that she wanted to roll on.
Yep - forgot the power cord and the foot pedal. The funny part - I knew I was going to do it, when I set the machine in the carry case. Mental reminders aren't enough.