Direct destinations in PAC file are sometime forwarded to proxy server

When I designated a PAC(proxy auto-config) file to ProxyPACURL in Global HTTP Proxy Payload, some destinations which is setteing in PAC file as DIRECT are forwarded to a proxy server.


[Global HTTP Proxy configuration]

<key>ProxyPACURL</key>
<string>http://intra-server/proxy.pac</string>
<key>ProxyType</key>
<string>Auto</string>


[PAC file]

function FindProxyForURL(url, host){
if( shExpMatch(host,"*.apple.com") {
return "DIRECT";
}

Code Block 
return "PROXY proxy.example.com:8080"; 

}

As stated above, apple related destinations such as init.itunes.apple.com, init.push.apple.com, etc, are supposed to access directly from the iOS device.
But some requests are forwarded to the proxy server(proxy.sample.com).
The percent of the forwarded requests is approximately 0.5%.

Is there a known information concerning this behavior?