Ha! I was just about to post same, when I saw that Della had already replied:
I assume the yellow "streaks" on the lower leaves were there from the start. If that's the case, than it was caused by environmental exposure, like cold. If you envision the affected leaves in their early stages at a single point in time, you'll notice that the lower leaves that are affected most would have been the most exposed in the sprouting stage, and would somewhat protect the upper inner leaves. The upper ones would only have had their ends exposed, and the yellowing symptom concurs. Definitely not virus.