Sure, every time anything happens to you, your state of mind is different. My point is that the relevant part of your state of mind doesn't necessarily change.

If you report a different number, that means some things in your mind changed. Those things may or may not include the level of pain you're experiencing.

Let's take an example with a bit more objectivity. If you ask me to rate how long a tv show is on a scale of 1-10 and I know the show is 30 minutes, how do I turn that into a 1-10 scale? Suppose I mostly watch shows with 12-minute episodes. This is relatively long, so I give it an 8.

Later I start watching hour-long shows. You ask me again how long this show is on a 1-10 scale. Now I put it at a 5. I don't think the show got shorter, and I don't experience it as being shorter. I just changed how I contextualize the length of shows for a 1-10 scale.

It would be silly to say that watching hour-long shows is a good way to shorten the mental experience of watching a 30-minute show.