LSASS is a System level process, so any kind of access to it will require Admin level privileges. I would guess that your user had admin access and you didn't realize it. You can check your level of access through a batch scriptcheck your level of access through a batch script to confirm. If you still have access to the machine you RDP'ed in to.
To the best of my knowledge LSASS has always been a protected process. It's needed for user login to for distributing access tokens so it definitely wouldn't be a user level process.
