hi.
in next releases i am gonna add tracking of head with simple led (not the big bulb). so pelase stay with us.
right now I can tell that if you reinstalled steamvr then driver4vr should be also gone. i have seen this message poping up no matter if someone installed or not new driver.
One thing to check is run command prompt, then execute vrpathreg.exe from folder
C:\Program Files (x86)\Steam\steamapps\common\SteamVR\bin\win64
Check if you have some path to driver4vr folder. It should be removed by uninstaller.