It’s sad but true, a lot of America’s roads are in terrible shape. A product of time, weather heave, and perhaps bad paving in the first place often lead to cracks and seams in the roadway. Most motorcycle tires are rather thin and they can get rather squirrelly when riding over these seams. Sometimes these seams are filled with tar by road maintenance crews. While this is definitely better than a non filled in seam, the tar is usually rather supple and can get quite squirrelly itself. Also going over open seams while turning could potentially make your tire loose traction when it hops over the seam.
Best practice is to try to stay away from seams and cracks if you can. If you can ride in a lane without one, do it. If the lane with a seam is the only option, try to ride in a position in the lane that minimizes the amount of times you come in contact with the seam.
When I cross over a seam, I don’t do it gingerly, I find that if I get some good momentum and lean going across the seam, it’s more seamless. (pun intended)