Yeah, I'm having this issue as well. I just got mine yesterday, and when I took it outside today at around 6pm I could hardly see the dot at all. The green dot seems to be much brighter than the red, but my understanding is that the green is supposed to be for indoor use and shouldn't be as bright/brighter than the red.
It's wierd, because I've owned 2 different pairs of Vortex binos and one riflescope and their quality is second to none, regardless of price (and I've owned Swarovski EL's, so I can say that). I have an NcStar piece of crap red dot for my paintball gun, and it's lowest setting is brighter than my Strikefire on the highest setting. This just doesn't seem consistent with the company, so I'm pretty sure I just got a bad unit. I'll probably be calling them sometime on Monday.