break in period?

[radio nut]

I have read stories about how stereo amplifiers seem to have a change in sound quality after being run for a number of hours.
Is there a break in period for electronics?
My muntz television had an issue and I have not run it in a couple of months not too mention that it does not have much time on it since being repaired.

I fixed the issue yesterday and have left it running. All new caps and nos tubes. A LOT of resistors also changed.
It seems to need an adjustment here and there since. As an example Verticle size and linearity and contrast.
Is this Normal?