Did you or your friend have firevault on?
I would suggest turning it off both when making the usb and when booting up on another computer with it.
I have made a usb on one computer and then booted up from it and installed onto another computer so it should work.
But I think maybe firevault could cause problems both for the usb and another computer if it is turned on.
I know this is a little off-topic, but there is a way to make a bootable DVD instead if your usb doesn't work. It's a bit more complicated and it will take longer for the DVD to boot up, but you could try it if your usb fails for whatever reason:
After downloading the Install OS X Mavericks.app file from the Mac App Store, run these 12 commands in Terminal to create a Mavericks.iso file and then burn it to a dual layer DVD with Disk Utility. You may then boot up from it by holding the option key down and then install mavericks. This will not install a recovery partition. To do that, uncompress and run the script file
https://dl.dropboxusercontent.com/u/13872235/Musings/Recovery%20Partition%20Creator%203.7.zip
hdiutil attach /Applications/Install\ OS\ X\ Mavericks.app/Contents/SharedSupport/InstallESD.dmg -noverify -nobrowse -mountpoint /Volumes/install_app
hdiutil convert /Volumes/install_app/BaseSystem.dmg -format UDSP -o /tmp/Mavericks
hdiutil resize -size 8g /tmp/Mavericks.sparseimage
hdiutil attach /tmp/Mavericks.sparseimage -noverify -nobrowse -mountpoint /Volumes/install_build
rm /Volumes/install_build/System/Installation/Packages
cp -rp /Volumes/install_app/Packages /Volumes/install_build/System/Installation/
hdiutil detach /Volumes/install_app
hdiutil detach /Volumes/install_build
hdiutil resize -size `hdiutil resize -limits /tmp/Mavericks.sparseimage | tail -n 1 | awk '{ print $1 }'`b /tmp/Mavericks.sparseimage
hdiutil convert /tmp/Mavericks.sparseimage -format UDTO -o /tmp/Mavericks
rm /tmp/Mavericks.sparseimage
mv /tmp/Mavericks.cdr ~/Desktop/Mavericks.iso