Any way to be proactive and get the Win 10 upgrade? I just did a fresh install of Win7 pre-SP1 as well and so far I'm still going through all of the Win 7 updates.
It should not still be available. If the OS was installed before the close of the free upgrade (as in the OP's case), it's possible a flag was enabled to permit it to upgrade to 10 but the actual upgrade was delayed for some reason, possibly pending another install, or amount of free space, or something deeper. If the PC was upgraded to Windows 10 before, but then downgraded to Windows 7 at a later time, the key is still legit for Windows 10, and may be upgraded back at any time. Something in Windows Update's coding may then trigger the upgrade during a Windows Update on such machines. Other than that exception, fresh installs should not have that (I'm sure intentional) glitch.
There is a program called GWX Control Panel, that was popular for a while when Windows 10 first came out among people who wanted to avoid being forced to upgrade to Windows 10. It can enable/disable the flags that trigger the update, delete the updates that enable the telemetrics prior to the upgrade, as well as delete the automatically downloaded pre-installation files for Windows 10 that can take up several gigabytes of free space. It can still be used for that if you're getting the Windows 10 install screen when you try to run Windows Update. I haven't tested it, but you may also be able to use it to set the flags to
enable the upgrade as well.