It's really both. It is the first place to show normal wear, it's not a big deal, and it can be adjusted in both the gibs and the trap nuts so that you have full travel without undue effort at the cost of a little more backlash in the middle than at the ends. It only becomes an issue when it is severe, and even then it won't stop you from making good parts. Judging by the wear on your chromed ways, I think you have a good machine that should outlast you. Clean everything out as you're doing, then adjust your lead screw nuts and gibs for the most balance between mid and end travel. All will be well.
