Yes, the tendril should be dry. (The exception is if the tendril was damaged and dried up, it can give a “false reading”.) Gently turn the melon and look at the spot on the bottom NOW, if it’s white, it is confirming the green tendril that the fruit isn’t ripe yet (put it back how you found it). Dry tendril and the ground spot turned to yellow are the best guarantees if you’re not familiar with this melon, or new to growing melons. Growing the same melon for several years will educate you in how it grows – nothing beats experience! Don’t depend on “melon thumping” for ripeness until you’ve had considerable experience, it’s tricky.
If you live in a cooler climate (like me in W. WA, a poor melon-growing area), it can take much longer for plants to grow and ripen -- for some vegetables and fruits, as much as 50% longer.