As you noted, one must be a registered contractor to have lien rights in WA. In order for subcontractors to have lien rights, they must contract directly with you, the owner, or with your agent, the prime/general contractor. In order for the lien of the subcontractor to be effective, the person above them in the chain (who they contract with) must be registered. Only registered persons can create a lien. If you contracted directly with any of the subcontractors, then they would retain lien rights. (assuming that they are registered as well) If the facts are as you indicate and the general's license was expired prior to commencement of the project, anyone who contracted through him will not have lien rights, it is the subcontractor's duty to understand the status of the person with whom he contracts.
In situations such as this, they are dependent upon a given set of facts, often they will be in dispute. I would be careful with any additional work. You may want to discuss this situation with an attorney to discuss the detail and/or steps that you can take to preempt possible claims.
Posting questions and reviewing information received from AVVO does not create a lawyer client relationship and such information should not be construed as creating such a relationship.