Noise for a couple of minutes

Do any of you Grandmeister 36 owners experience any noise just after powering on your amp for a couple minutes? I power on the amp, wait a minute, then go out of stand by. Then I hear some static noise for a couple of minutes. It's pretty loud but then goes away on its own. While playing for hours after that, I never hear the noise again. I suspect the tubes are warming up or something like that, but have never experience this with a tube amp before.

Thoughts?

Hi,
Nope, I have not heard that....mind you I am now on my second set of tubes, cause I cannot help myself, LOL

Get those Chinese no names out of there.

I had a set of JJ power tubes (4 of them) and replaced the Chinese ones thinking they would sound a little warmer. The sound is about the same, but the noise has disappeared. I swear that the noise was there every time I turned on the amp, but I've only had it for 5 days now. Anyhow, keeping my fingers crossed that I had a tube causing the static sound.

I'll post again in a few days with an update.