Interesting behavior for summer squash

I just noticed this morning that summer squash tends to avoid competing with other summer squash. For some reason, when 2 squash plants grow close to each other, their leaves will detect the presence of the other squash plant and actively curl away from the other plant's leaves. Yet when a squash is growing near other plants such as beans, the squash leaves will grow into the space occupied by the beans, and try to block the sunlight of the other plants. Has anyone else seen such behavior?