Northern Lights Auto Fem Seedsman

Day 69, about 10 weeks from sprout. 41 or 48 (about 6 or 7 weeks) of flower. Despite keeping up with fertilizing I'm getting a lot of purple/red and leaf drops. This might be from too little fertilizer but I think it's mainly from the plant maturing. I know some growers have had their Seedsman NL Auto run longer than advertised, but my plant seems to be on schedule. They say 55-60 days of flower following 2-4 weeks of veg. Trichomes on sugar leaves are going amber but most of the trichomes on actual buds are clear