Hi, Blue Gum: Yellow squash and zucchini certainly will cross polinate, but the results are usually not seen until the fruit that grows from cross pollinated seeds in the following year. So this may be something that was in your seeds. It also might be because some sort of stress is changing/expanding the tiny amount of green that is on yellow sunbursts anyway. Sounds like cross pollination at some point, though.
Hi, Blue Gum: Yellow squash and zucchini certainly will cross polinate, but the results are usually not seen until the fruit that grows from cross pollinated seeds in the following year. So this may be something that was in your seeds. It also might be because some sort of stress is changing/expanding the tiny amount of green that is on yellow sunbursts anyway. Sounds like cross pollination at some point, though.