My PS came out to ~4600 characters (down from over 5300 in the first draft) and one of my PIs who also serves as an interviewer for the med school told me it was one of the best he's seen. Quality > quantity.
If you feel like you've said what you need to say and that the essay is as good as it's gonna get (reasonably), then you're good. If anything, adcoms probably value a shorter PS considering how many essays they have to read. No sense in annoying your reader with filler.

Wow, I can't believe they did that (okay, I can). That's hilarious, for all of June and most of July they were saying "don't worry guys, we may be going slower than usual but we will
definitely be able to keep to the 6 week turnaround we promised!" AAMC is really dropping the ball this year, they've gone back on just about everything they've promised so far.
Considering AAMC is still stuck on June 27th though, I think the old concept of when an application is late is going to be very different this year. It may be that this year even an October secondary submission will be "on time".