New Post: Upgrades out of order?

It appears that when an upgrade is installed, the newer version is installed fine, but before the older version is uninstalled.
Do you you if this is normal behavior of MSI's? Shouldn't it be that the older version is uninstalled first before the newer version is applied?
This is causing an issue for me where I'm calling some custom code (using InstalledFileAction) to install a service, and the service is removed after it is installed...