Ah, found the answer myself (https://groups.google.com/forum/#!topic/golang-nuts/-xnFsH_ZRqU). At least with `NewTimer`, the timer returned contains a channel on which a tick is sent. However, looking at the implementation of `time.AfterFunc()`, the timer returned from that doesn't get any channel assigned to it, so there's nothing to close in that case.

Compare:
http://golang.org/src/pkg/time/sleep.go#L62 (NewTimer)
http://golang.org/src/pkg/time/sleep.go#L109 (AfterFunc)