I've been keeping an eye on this topic as I just received my first PRO last week. When I mounted it and looked through it the dot was solid, no comet or line from 10-4 as described. I wear light reading glasses for the PC and reading, and the next morning after a bit on the PC, I picked it up and looked through it. Horrors, the line was there and the dot had a tail.
Since then I have randomly picked up my rifle and sighted through the PRO when I haven't had my glasses on for a bit and the dot is solid and no lines appear anywhere. If I've spent an hour or more with my glasses on I see a very slight comet effect in the house or outside, natural or artificial light makes no difference. I haven't noticed a line since.