K & G Construction Co. was the owner of and the general contractor for a housing subdivision project. Harris contracted with the company to do excavating and earth-moving work on the project. Certain provisions of the contract stated that

(1) K & G was to make monthly progress payments to Harris;

(2) no such payments were to be made until Harris obtained liability insurance; and

(3) all of Harris's work on the project must be performed in a workmanlike manner.

On August 9, a bulldozer operator, working for Harris, drove too close to one of K & G's houses, causing the collapse of a wall and other damage. When Harris and his insurance carrier denied liability and refused to pay for the damage, K & G refused to make the August monthly progress payment. Harris, nonetheless, continued to work on the project until mid-September, when the excavator ceased its operations due to K & G's refusal to make the progress payment. K & G had another excavator finish the job at an added cost of $450.

It then sued Harris for the bulldozer damage, alleging negligence, and for the $450 damages for breach of contract. Harris claims that K & G defaulted first, having no legal right to refuse the August progress payment. Did K & G default first? Explain.