Haley, could be. Well I should have my GC 0w30 coming up soon and it will have 5K on it with about 6-7months on the oil. Some say it may be a coolant leak, but I haven't seen any drop in coolant.
Do you do a lot of driving near the ocean? I've heard that you can pick up a lot of sodium through your air filter from salt dust. Since your second UOA has relatively high silicon, this is feasible.
I noticed that my UOA have high sodium content. The car only has 30K on it 5sfe Camry. Each UOA was either 3-5K, but it takes me about 6mo to reach that point.
Is there a correlation between Sodium content and long drain intervals (time not mileage)?