I think you had an abnormal melon that might have been effected by the hole that had been chewed into it. I always look for a dull sheen on the outside and ALL of the nearby tendrils brown and dead. Not just one. The first melon of the season is always the hardest one to judge. It's kind of like a sacrificial melon.

That looks a little like spider mites. Are there very small insects on the under side? It could just be lack of fertilizer and aging leaves.

I've never had a good melon that was odd shaped. The shape indicates incomplete pollination. Also it's too small to be really good. The best melons are medium to big size. But it will be ripe when the tendril by the stem turns brown.

Can't see any pictures. But, there is a little curly vine right next to the melon stem. When it shrivels up and dies, the melon is usually ready to harvest. Also, turn the melon over...the belly should be a creamy, light yellow color when it is ripe. Lastly, but, least importantly, some people 'think' they can tell when a watermelon is ripe by thumping it with their finger. If it makes a hollow sound, those people say it is ripe. Harvesting Many home gardeners experience difficulty in determining when watermelons are ripe. Use a combination of the following indicators: (1) light green, curly tendrils on the stem near the point of attachment of the melon usually turn brown and dry; (2) the surface color of the fruit turns dull; (3) the skin becomes resistant to penetration by the thumbnail and is rough to the touch; and (4) the bottom of the melon (where it lies on the soil) turns from light green to a yellowish color. These indicators for choosing a ripe watermelon are much more reliable than 'thumping' the melon with a knuckle. Many watermelons do not emit the proverbial 'dull thud'when ripe. For these, the dull thud may indicate an over-ripe, mushy melon. Please see the link to learn all you ever needed to know about watermelons. Here is a link that might be useful: University of Illinois Extension: Growing Watermelon