I've used Leupolds since the early 70's just out of high school. While in HS I had to use what I could afford, (a cheap beat up old used Weaver) but it did ok. After that it was nothing but Leupold for me until about a year ago and I found that because of my aging eyes I was seeing double crosshairs and I couldn't adjust the eyepiece far enough out to compensate for my eyes. So I started looking at something else and found that the Swarovski Z3 line worked with my eyes and had plenty of adjustment left.
So I started on a project to replace all my scopes with Swaro Z3. I've been handing down my Leupolds, most are VX3, to sons and daughter-in-laws who are happy to get them.
If it hadn't been for that I would still be using Leups and you wont catch me bad-mouthing their quality.
I started having the same problem with Leupolds and fine crosshairs (my favorite reticle), I mentioned it to my opthomoligist at my last checkup and he said that it caused because I was starting to develop a slight bit of astigmatism, which is correctable by glasses or contacts. I have found that it is not issue if I use a scope with the standard duplex which has a slightly heavier crosshair.
You might want to get an eye checkup to see if you are having the same issue.