Has anyone else noticed steaks on their teeth from using Plus White tooth whitener? I've been using it, and I just noticed that I have almost brownish (faint) streaks on my 2 front teeth! My wedding is in 6 weeks. Any suggestions on how to get rid of these?!? I had never noticed this before using Plus White. The rest of my teeth are definitely whiter, but what's up with the streaks? Thanks!