If you have a qualifying OS for the free upgrade to win10 (and you appear to have), then on your normal windows updates you will have received one that effectively is in preparation to upgrade to win10. Now you may not have been aware of that that KB was for, but in effect you reserved/agreed to upgrade to win10. So MS went ahead and downloaded all of the GBs of stuff in readiness of your upgrade to win10.

So yes it could be related, but it could also be MS downloading lots of files to cope with many eventualities, OS you have or CPUs, etc.