Depends on your goals and other stats. It's kinda hard to just look at the MCAT in isolation. A 510 is low for someone who has a 4.0 and 1000 hours of research gunning for Harvard, but that same score is good for someone applying to their state MD or a DO school.
Probably the only definite MCAT re-take situation would be if you had much higher practice scores taken in realistic test settings and something bad happened the day of your actual test.