It could be insects such as grasshoppers or from a dry spell followed by heavy rain.* There are other possiblilites as well.* Scroll 3/4 of the way down the page at this first site to 'Splitting'.
See #12 under 'Fruit' here.
Here's what grasshopper feeding injury looks like.
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.