Help? Three positive OPKs in a row? Photos and chart

Hi everyone,
I've been taking one OPK every morning at 7am for the last 8 days. For the first five days they had a faint line that was definitely not as strong as the test line (thus no lh surge). 
Two days ago I got my first positive. Then yesterday it was positive again (I thought it looked very slightly darker. Today I was expecting to get a negative but again it was positive. That's 48 hours at least of Lh surge. 
Does anyone have any thoughts? Has this happened to you before?