Tung-sol 12ax7 in V4 in mark IV?

My lead channel of my IV was extremely noisy, so I was going to swap out V4 but didn’t have a spare AT7, but I had a brand new tungsol AX7.

Is it a big deal? The noise is gone and the lead channel sounds great, but I haven't read anything on whether it is safe or not. I know the at7 has less gain, which gives more headroom(?). Only played on it for a few minutes to verify the noise being better, but better safe than sorry.

Any insight?

Do you have a Mark IVa? That is the Revision that uses a 12at7 in V4. In the IVa V4 only effect the reverb, and the amp can be used without a tube in that position at all as long as you keep the reverb turned down.
The IVb uses all 12ax7s, so if you have that revision V4 is designed to be used with a 12ax7, not a 12at7.