Throat erosion rate?

I wasn't sure where to post this question. I've been using an RCBS Precision Mic for my 110fp, 308 to determine bullet seating depths. The rifle is around 10 years old now. I have always loaded for it and have kept the load velocities below max listed levels. I use mostly the usual powders from IMR and lately Varget. Bullet weights range from 155 - 175 grains. I double checked the chamber tonight and found that the distance needed to touch the lands on the mic has increased by 0.015" over the years. Is this normal? I checked and re-checked the mic reading several times and it's always w/in 0.001" of my initial measurement. I shoot intermittently throughout the years and maybe sent no more than 2000 shots down range. Any thoughts?

You have 8000 to 12000 more shots to go. 15 thou is nothing.....as long has the throat is not cracking from heat and the barrel stays accurate, keep shooting it.

The 308 is the odd duck of the world.....not enough case capacity to use enough powder to cause serious throat erosion.

Keep the heat down and keep shooting it.