crawled data in content are difference from fess12.3 to fess13.4

I did FS crawler job with fess12.3 and fess13.4 to crawled same file(excel file),and found a little difference from [content] filed:
In fess12.3 [content] filed "\" is included.
In fess13.4 [content] filed "\" is disapeared.
Please see attached picture.

Is there something changed in crawler function with version up?

What is a problem? A new version has a lot of fixes.