It happens a lot more in the summer when temps are higher. Don't worry about a few new white hairs when determining ripeness. Also, I've never seen someone harvest a bud too late, wheras 90%+ of new and intermediate growers harvest too early. I even know some guys who grow spectacular plants who started harvesting too early 30 years ago and just continued doing the same thing every harvest since. If you are coming up on a harvest, post a few good pics here, close up and whole plant and then see what some of us think here. And the advice to "wait another week when you think they're ready" is good advice. Actually, waiting two more weeks when you think they're ready is even better for new growers. The biggest thing homegrowers have going for us over commercial operations is that we can actually harvest our buds when they are ripe. That's the main reason why good homegrown bud blows people away who haven't had it before. Dispensaries sell immature bud with extremely dubious THC "tests" showing inflated %s. Sorry, went off on a tangent there. Here is one of my favorite little write-ups on signs of maturity beyond just scoping trichomes for some arbitrary % of amber: