I have been getting "Not Secure" messages up in that little line with the star.

Recently, when I am reading threads on DU, sometimes I have noticed little "Not Secure" messages up in that little line with the star, instead of the little black lock that is supposed to be there. I always immediately click out of that thread and start over in Latest Threads, and it goes away. I am not computer savvy, being a 72 year old bookworm. Maybe it is just a common little glitch? Anyway, I thought perhaps I should mention it to other DU people.