[Plugin: Better WP Security] file 404 errors for files I don't have

I see an 404 error for this file /submit-articles It doesn’t tell me more than that.
I believe hackers are checking to see if I have these files or directories on my site. I don’t believe I do but I thought I’d ask. I get on average 30-40 404 errors each day but I’m not sure why or where the files may be causing the errors. Sometimes it’s a blog article causing the error and I don’t see a problem when I access the same article…

Thoughts? Maybe the 404 errors could be more descriptive on the error.. Was it one time or everytime it’s opened?

http://wordpress.org/extend/plugins/better-wp-security/