Why is there a `@Received(1): "X"` in the output?

gistfile1.go

package main

// $ go version
//go version go1.0.2

/// OUTPUT (made with echo test | nc -v -w 1 -4 -u 127.0.0.1 1234)
// 2012/06/24 16:22:47 @Received(1): "X"
// 2012/06/24 16:22:47 @Received(5): []byte{0x74, 0x65, 0x73, 0x74, 0xa}
// 2012/06/24 16:22:47 @Received(5): "test"


import (
    "flag"
    "fmt"
    "log"
    "net"
    "os"
    "strings"
)

var (
    host = flag.String("host", "localhost:1234", "the port to listen on")
)

func main() {
    log.Print("@Booting...")
    flag.Parse()
    log.Print("@I need to listen here (flag): %s", host)
    laddr, err := net.ResolveUDPAddr("udp", *host)
    log.Print("@Trying to listen on (UDPAddr): %s", laddr)
    if err != nil {
        log.Fatal(err)
        os.Exit(1)
    }

    l, err := net.ListenUDP("udp", laddr)
    if err != nil {
        log.Fatal(err)
        os.Exit(1)
    }

    go func() {
        for {
            b := make([]byte, 1024)
            r, err := l.Read(b)
            if err != nil {
                log.Printf("@Error: %s -- next round!", err)
                continue
            } else {
                s := fmt.Sprintf("%s", b[:r])
                s = strings.TrimSpace(s)
                log.Printf("@Received(%d): %#v", r, b[:r])
                log.Printf("@Received(%d): %#v", r, s)
            }
        }
    }()
    fmt.Scanln()
}