Sourdough tartine country loaf ; crumb too moist

Toast
The crumb is too moist

How long did you let it cool before cutting into it? Looks like it rose nicely, so I don't think there's too much water in the dough. So either you cut into it while it was still hot, or you need to bake it a bit longer (at a cooler temp if necessary).

It looks like it was sliced while too warm.  See how the inside has shrunk back, leaving the crust overhanging a little?  That's a tell-tale sign. If the crumb stays a little gummy after the loaf has sat around and cooled well, that would say that more baking was needed.

TomP