These days most communication I would say I do via electronic methods - Twitter DM, E-mail for example.
So I suppose the question is would I have sent my boss a similar message.
' DS was disappointed that no one was able to watch his rugby match today. He said what is the point of having parents if they never come to see me '
To be honest, I wouldn't have sent that.
While some posters on here would want to be told that their child said this, I would not raise that on the first occasion of the child saying it (was it the first time the child has raised the issue?). Instead I would have had a chat with the child concerned, dug a little to see if there was a reason behind them saying such a thing - they are after all saying it to me, not saying to their parents... so maybe they were trying to get a reaction from me. Peer pressure can be an issue, if everyone else has a parent watching them play a match, they want a parent to watch. But that isn't always possible when both parents are working (or ill, or for whatever reason can't attend every match, especially away matches).
"He said what is the point of having parents if they never come to see me."
I would have seen that as being the child letting off anger, thus something I would have dealt with directly with the child... not passed it to the parents to deal with. If having had a chat with the child they still kept on with that attitude then I would raise it as a more general concern about their attitude towards comparing themselves to their peer group. Children need to understand that mum and dad work... they can't be at every match they play at school.
I'm not sure if there is a right approach to handling this kind of comment from a child. Some parents will want a nanny to tell them everything that happens, others may prefer the nanny to deal with it. It can be a tough call sometimes to decide what is something you should tell parents about and what can be dealt with there and then. As this was a temp nanny, maybe they didn't feel able to deal with it themselves... though I don't feel there was a need to convey the second sentence of the child's comment... that I see as being the child's anger coming out at the time... something they may not feel after thinking about the situation for a while.