I noticed this earlier in the year. I would login to update my DNS and one of my assigned name servers was red more often than green. In frequently, my domain would not resolve. I was a customer for what would have been 10 years in October.
My solution: I switched to dnsmadeeasy. More features, more nameservers, better pricing, better payment system, better panel, better statistics and the best uptime... to name everything I can think of. Nothing but a great experience!