Brown Tips on some leaves - too much nutrients?

I also think it is a bit too much fertilizer. Everything else is looking fine though so I would not mess around with anything else in a panic. Your best bet would be to go about 25-50% less in your next feeding. This should straighten it out without skipping a feeding. My guess is this is happening due to too much salts (nutrients) being left in the soil when the media drys out. Remember you should ALWAYS water enough to have roughly 20% water run out the bottom. This will help rinse out the old salts left behind and avoids any nutrient build ups in your media. This is a common issue around week 5-7 because growers are not getting enough run off after every water. I think your plant will sort it out and bounce back. Good frost production so far as well! Hope this helps.