Strange SCREEN on this CRT

I lowered the SCREEN of a CRT, as it was evidently too high, and now the black is completely black, but by turning off the room lights completely and remaining in the dark, the lines can still be seen and the black is a little red, can this be a problem and would i notice something similar when i use it daily, obviously, with the lights on?

Then after a few days i turned it back on, and the lines were visible, but they slowly disappeared (always with the lights off), but they were still visible if I glued my eyes to the TV

.After a while they disappeared, and now it's black, as it should be, what does it mean?

Is it something off or is it normal?