iPhone iOS 4.2.1 / GMail Exchange / Mails missing?

Just in case someone else has this very strange problem:

Using GMail on the iPhone via Exchange and there are mails missing in the iPhone inbox? Not every mail from your GMail inbox showing up on your iPhone? In my case, there were certain mails not showing up. It didn't matter if the missing mail was only one of two or the 29th of them. It wasn't a matter of the send date neither.

iPhone 4 with iOS 4.2.1

General Mail Settings:
- Fetch New Data: Push
- Show: 200 Recent Messages

GMail Exchange account's settings:
- Mail Days to Sync: No Limit
- Mail Folders to Push: Inbox

This drove me insane and to switching to IMAP temporarily. Then I've read this
http://forums.macrumors.com/showthread.php?t=1043418
and one guy suggests sending yourself a mail to your GMail account from another account.

What can I say? It worked for me. All mails showed up after receiving the new mail. Crazy. Especially if you keep in mind that I received multiple emails from other people before and that didn't help.