The "Seller's Disclosure Form" should have had mention of this, but this past spring was an incredibly wet one, even by New Hampshire standards.
My neighbor's new house was built into very soggy clay soil, so they tried installing a "French Drain" on both sides. (
Tried, because it kept washing away this spring!)
A "French Drain" is layers of crushed rock or shell buried under the topsoil, shunting the runoff around the house—to your neighbor's! (Just kidding).
As a temporary measure—and if the seam is accessible with a little digging—you could try putting sawdust along the seam. If it shows up in your sump-well, then you DO have a problem. Sawdust should flow into narrow cracks, slowing (maybe stopping) the flow. IMHO.
