Sad event and condolences to his loved ones.

Considering his age, the trip up here from SoCal may have been the cause. Protracted sitting, especially when driving, can cause deep vein thrombosis that then may lead to a pulmonary embolism. I only mention this so that others who decide to drive long distances might remember to take breaks and be sure to flex those leg muscles frequently while driving. This issue is more common for males, especially tall ones, than for women or short folks. (This is one reason I'm a fan of Amtrak, where I can get up and walk around any time I want.)