Purple line??

So I am 38 weeks 5 days today and came across a post about checking for a purple line on your butt crack to check for dilation. So of course I had to run to the bathroom and check and there's a huge purple line! I want to show my husband to make sure I'm not imagining it but then again, he'll be seeing enough of me here soon! I was 80% effaced and not dilated at all this past Monday but I know things can change quickly. Do you ladies think there is any accuracy to this purple line or just another weird symptom? I'm trying not to get my hopes up!!