Yes, she should have been watching, but things happen, and she will be more aware of it now. I wouldn't actually ever use a childminder, because regardless of how flippant I might sound I only ever would look after my own child until it was at the very least past the toddler stage. I wouldn't trust anybody else except close friends and family - the people I know love my child and would give it individual attention.
As I said though, times have change. It has become normal for kids to go to childminders and nursery at a very young age. We were far from rich, in fact we didn't have two pennies to rub together, but our lifestyle expectations weren't so high.
OMG, I sound like a real old timer now!! ;o)