My assistant dropped the ball

[Dreamalittledream]

Ouch! Feel your pain; trying to backpedal and explain yourself is a hard hole to dig out of once that negative seed is planted. So how'd you handle it with the parent that happened to be there that day? I would hope that any parent, given the explanation you just gave us would understand (that your assistant was there keeping an eye on child that other lady thought you left in her care).
Not sure if you're already going to do this but.... I would also address it with 'other lady' as well next time you see her..."thanks so much for your help the other day, just wanted to make sure you didn't think I had left the child alone, my assistant was right behind you"...something to cover your butt