Does a long LH surge mean anything? Good/bad?

I have only sporadically used OPK's (I use wondfo's) and typically see the lines get gradually darker until it's positive. The next day, it's generally much lighter/negative.

This month, it's been super light until one day, BAM. Super positive. Three days later, it's still very positive. The 1st positive came a few days after I would have expected it to, as well.

I don't do BBT, so the only info I have is from the wondfo's, which probably isn't very helpful.

Any ideas?