popping sound with new 6922 tube

I am new in the tube world. I just replaced Siemens 6922 tube with Phillips. When I turn the preamp up for the first time in the morning, I get a popping sound (probably from tube) after a couple of seconds. A noise is delivered to speakers, too. Is it ok? Will it disappear as the tubes age? Or should I get a different pair? Thanks for your help.