when my amp is off i hear noise coming from tubes

[MetallicaFreak65]

when i turn my mkiv off aftwords if you listen you can here little dings coming from the tubes. there brand new so i can figure out why its doing it. sounds like someone is tapping on the tube
is this them cooling down? it happends about every 30 seconds
HELP

 

[212Mavguy]

When things get hot they expand, when things cool, they contract. No biggie. They probably do the same thing when getting hot. Nothing to worry bout.

 

[MetallicaFreak65]

thats what i thought thanks