It has nothing to do with your Hosting accounts (reseller or otherwise) with TCH, only the domain registrations which is completely separate from hosting.
TCH used a service to process their Domain Registrations (ie: not hosting stuff, just domain registrations) and I'd venture to guess that something happened to that account. Likely it was accidentally let to expire.
It's hard to explain without mentioning who TCH used to sell their domain registrations (again, registrations, not hosting) which I'm not sure they want mentioned yet.
Just know it's a large reputable company, just like TCH, and that in my opinion you have no reason security wise to be concerned with TCH or Domains Priced Right.