I would argue that you should own a set of head space gauges for all calibers you shoot or get them checked out from time to time. "New" doesn't mean safe, I've learned that the hard way.
With some guns the head space stays pretty rock solid, some guns it moves very quickly as parts fatigue and wear: M305s are realy bad for it. Bad headspacing can cause a large amount of damage to your gun, it can seriously injure you, it can injure people next to you, IT CAN KILL YOU.
you wouldn't drive a car with a loose head because 2 thou out of spec and its pissing gasses from the pistons out and coolant is leaking everywhere. within short order you blow the motor.
If your guns not operating within spec even just 2 thou out, why would you trust it to create an explosion 3 inches from your face? An explosion that has enough power to hurl a 150gr piece of lead 1000m before it goes through your body. If the case head separates, it can put the bolt through your head, if your hand is around the mag well you may very well need 40-100 stitches to put it back together if you don't lose it. Even if you escape the shrapnel the hot gas can burn and blind you. I have had rifles blow up on me... when my ruger went, it peppered the firing line with pieces of the stock and mag, the hot escaping the back and deflecting off the scope bell burned a hole through my cheek, if I hadn't been wearing ballistics I might have very well lost my right eye.
Its $50 for a set. They last a lifetime if you look after them, you can use them on all your .308 rifles.
buy them, use them; if its out of spec stop firing the gun and fix it.
here is a video of a deliberate bad head space condition (for training) and what happens
here is a person shooting a AK that had bad headspacing (from factory)
.308 falls nicely inbetween these rounds