Red blood line?

[Chloesmama]

Hi!
It's my first time incubating eggs and it is not going so well. The humidity was all over the place for the first 3 days and even now I have a hard time keeping it at 40-50.
I have candled the eggs a few times and have veining in all of them, but today I noticed a red line on some of them. I am not sure if it is because of my light or if they died.
What do you think?
Edited to add- today is day 7

 

[AltonaAcres]

I still see other veins so it should be ok. If there's just one big line, that is blood ring and it died.

 

[ChickNanny13]

Looks good to me