Clearblue OPK straight to solid smiley

First cycle trying since we had our son 20 months ago.

I started testing early this cylce, because I recall getting a positive opk much earlier than predicted last time I got pregnant, and I went straight from a negative result to a solid smiley positive result.

Well, the same thing has happened again. Straight from a negative to a solid "peak"

smiley.

Reading the Clearblue booklet, it's looks as though this means I don't get a rise in estrogen high enough to be detected before I ovulate?

Anyone else experienced this? Not that it matters because I seem to be able to get pregnant anyway, I'm just curious as to what it means.