This is quite common in tanks with relatively new aquasoil. It is simply leaching nutrients into the water column.
Your tds isn't anywhere near being problematic. The only inconvenience I can see it causing is if you intend to breed something that requires ultra low TDS.
Everything else being equal, TDS will almost always rise since the bacteria is breaking down solids into nitrate and other compounds, so it isn't really anything to be worried about.