Thanks for reporting this, I've fixed it using slightly different approach:
-%{_libexecdir}/%{name}/smartdnotify
-%{_datadir}/%{name}/drivedb.h
+%{_libexecdir}/%{name}
+%{_datadir}/%{name}

because it's not expected that any other package adds any file in those directories

Thanks, that's a perfectly valid approach, I just chose to add specific entries because the specfile already contained fairly specific %files listing.

BTW it's not relevant if another package chooses to install files to those dirs, it's just a matter of how closely you want to keep track of the files installed by smartmontools (for example in case new files appear or old ones disappear between versions etc or depending on the build flags).  %files entries like %{_sbindir}/* would not cause any non-smartmontools files to be included in the package in any sane package build environment.