2018 Mitsubishi Outlander — service history disappears for three years

This started as a small annoyance and I finally decided to track it down. 2018 Mitsubishi Outlander SE, about 67,500 miles. The car has dealer records early in life, then a long blank period, then records again. Seller says maintenance was done independently. Is the gap itself a concern or mostly a reason to inspect condition and ask for receipts? I am in Boston. If I figure it out I will update the thread.