My guess is that there's an unneeded tab stop in the TOC1 style. If you modify the style and go to the tabs menu, I think you'll find a tab setting at the same position as the first tab showing on the ruler in your screen shot. Note the position and delete the tab in style TOC1. However, you might need that tab in TOC2, which I expect is based on TOC1, so you might have to modify the TOC2 style and restore the tab setting for that style.