preg_match() compilation failed

I am working on a demo site at http://ameralia.net/bundyorganic/ and so far all had been well. Today I edited an existing node, and after submitting, received this error - repeated 45 times down the page:

warning: preg_match() [function.preg-match]: Compilation failed: PCRE does not support \L, \l, \N, \P, \p, \U, \u, or \X at offset 3 in /home/sites/ameralia.net/public_html/bundyorganic/modules/pathauto/pathauto.inc on line 72.

I'm afraid I don't know a whole lot about drupal and php, but as the error references pathauto I thought perhaps you might be able to provide some input- the node in question looks fine and I don't see any indication of any other problems as a result. Is this something I should worry about? Thanks in advance.