@greatdragon - first the disclaimer - I am not a regex guru, I know the basics to get by. However note that it is a \s* not \s+, so it should make no difference to your pdf, as it is 0 or more matches?
I can't remember all the reasons why it is there, there have been many iterations of this plugin over its lifetime to get to where it is today. It may have been to catch some case I can't recall. Or it may have been to "soak up" leading spaces to prevent a document with loads of consecutive spaces reporting as matches (since space is a valid character in the next part of the expression).
Now if others who know far more about me than regex agree with your finding then I can look to change it, but I am firmly in the "if it ain't broke don't fix it" camp.
Performance isn't a reason if the change were to reduce its effectiveness for some reason, particularly since it runs as a background job.