I'm experiencing the same issue, but I only noticed it starting on 8/1. Jeez, I thought I was either crazy or the latest Air kernel was screwing things up. I ended up swapping between diff kernels, reflashing my rom but nothing helped.
Glad to see I'm not the only noticing this.
---------- Post added at 01:50 PM ---------- Previous post was at 01:43 PM ----------
And just to confirm, the event colors are only darker in the google calendar app. If viewing the calendar in your mobile browser, the colors will be correct.
Android - O YEA!
-Droid X (2010)
-Droid X2 (2011)
-HTC Rezound (2012, retired)
-Galaxy Nexus (Toro) (2012, current)