Had to reboot half-way through Lion download, now it wants to download the whole 3.7GB again

Started downloading Lion through the AppStore but had to reboot half way through (there was a need to reboot into windows). Since this is the year 2011, I foolishly assumed we've got decent caching mechanisms, and that AppStore would resume where it left off, just like every other download manager that exists today. Imagine the nasty surprise I got when restarting the Lion download and install, it starts from zero, and has to download the whole 3.7GB again.
Am I doing something wrong or is this the default behaviour?