Ringing new NOS tube, is it safe?

Dear all,
Need some advices.
I bought NOS 12AX7 tubes from a reputable source (never saw any complaint about the seller) about 3 months ago for my phono preamp.

However, I start hearing ringing sound/noise from the tubes (not from the speakers). Is it safe to keep using it by dampening it with tube damper?
Is it possible that there is something wrong with the preamp circuit that might cause the ringing tube?

Thanks in advance for the advice
No- the circuit is fine. The tube is microphonic. It won't hurt anything, but generally microphonic tubes don't sound as good.

If its still in warranty get it replaced immediately- most warranties are only 90 days.
Certain vintage tubes have a tough time in phono stages or in high gain line
stages because of microphonics and/or other noise. You have to consider the
gain of the position you're putting the tube in, plus the net downstream gain.

Some tube sellers have various grading scales which indicate where the tube can
be appropriately used -- e.g. Upscale Audio's Platinum Grade tubes are good for
phono stages, whereas a Driver Grade tube will be too noisy in that application.
Some sellers don't test/rate for noise/micro, which makes it a gamble. In my
experience, the older 6SN7, 12BH7, and tall-plate 12AX7 tend to be problematic
in high gain positions. So you don't really have a complaint against the seller
here unless it was advertised as a super low noise/micro tube.

Some people report that tube dampers and/or component footers help a bit.
The tubes are crap you got taken!!Try Vintage Tube Services one of the few honest venders.
Some NOS tubes are sensitive to micro-phonics and tube dampeners can help. This does not mean the tubes are junk or defective. If you purchased them from a reputable dealer he/she will understand and should replace them. I am in agreement with Mulveling. Good Luck.

Generally speaking, if a tube has problematic microphonics, a tube damper isn't going to help.