Uber Purging Bad Ratings?

Does anyone notice inconsistencies in their rating summary and the weekly rating reports? In the past couple of months, I've had a 1 star and a 2 star on my weekly rating. The 2 star never even appeared in my rating summary. The 1 star appeared in the calculation for a few weeks and then dropped out. The rating page says they still calculate it on the last 500 rated trips. Either they've dropped that number down or they just seem to purge bad ratings from my calculation.