It is not an issue of AllowOverride(yes, Apache's default is All)
It's simply a logging of the fact, that a file was'nt found, an 404-error.
You should find the same entry inside the access_log.
If you don't have further problems with this logging(maybe your space is rare, so you have to avoid it), you could leave it as it is. If you don't want errors of the level "error" to be logged, you can modify the log-level inside httpd.conf. Find the line starting with LogLevel . Change the following word(maybe: warn, error, notice, info, debug) to crit ->then restart the server.
But do this only if you have good reasons, because if you do this you don't get any error-level-errors logged in the future, and there are more errors than missing files.
Regarding to the question how to add AllowOverride:
you can put these directives onto httpd.conf inside every
<directory/>-Section. For example: