If a CRT PCB has dark spots on the board, does that mean it's a high hour set?

[CRTguy]

I have a Panasonic 27" CRT from 2001 (Model CT27D11E) and I took the boards out to clean them. I noticed that 3 different parts of the main board were a much darker brown than the rest of the board. More specifically, this was in the power supply section and vertical and horizontal deflection areas. I'm assuming this is from when the board would heat up during use and eventually it got hot enough that it darkened the PCB in those areas. I will note that in the areas where the PCB is darkest, that is were the components are really crowded and packed into a very small space.

When a CRT PCB gets darkened areas like this, does it mean that the TV was used a lot? How many hours of operation would it take for a PCB to get darkened areas like this? The tube in this set is still bright and sharp and the colors still look vibrant.