I think I lost my Mucus Plug

Brittany • 27. Finally got my BFP after 11 cycles of TTC by using the SMEP, Preseed, and a whole lot of prayers!!
I didn't take a picture but I just went to the restroom and noticed I was slippery when I wiped and I was spotting brown a bit. Then I wiped again an a large amount of mucus came out. It was about the size of a teaspoon or possibly a tablespoon. It wasn't red or bloody like some of the pictures I've seen. 
I'm 38 weeks and 2 days today. Is there any reason for concern? I've been having light contractions today but nothing unbearable. I did get my membranes swept on Wednesday and she said I'm 1-2cm. 
I'm trying not to freak out but something like that coming out of me has me feeling a bit uneasy. 
Can someone offer some advice? Could labor be soon or could I still hold out until his due date?

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