How do I spot this Missing file (Causing errors)?

Hoping someone in here can help me out...

I have this error coming up in my error logs which I don't know how to get rid of.

It appears as a css file, like this:

[Sun Jul 07 01:28:12 2013] [error] [client 58.108.134.53] File does not exist: /var/www/html/mlmbeat/a02124fdb3e8535486f33d63ec936622.css

How would I find what is searching for this missing file?