Yesterday I did a similar test. While that email arrived in Hotmail Webview and my bada Phone, PB didnt receive, despite of Push. Checked the account settings. Not the usual "connection lost" status message.
Rebooted the PB -> email was pushed.
One of the bad bugs I encounter all the time. I had few devices rrecenbt years that I had to boot that often to continue to work.
I'm having a similar issue, i get the notification light and message top left of playbook, if i press it and open the mail app the emails are not there. i try to refresh and nothing.
If i quit out of the mail app and re-open then they are there, or if i go to the mail settings and make a change then they appear.
It also has an issue that if the above is happening then when i choose to delete a message it wont show it as deleted until i re-start the app.