Why did this photograph turn out this way?

This morning I took a few pictures outside of the frost, but when I downloaded them I noticed that one of them had this beautiful, faded vintage-y look to it, but none of the others did. Here's the picture:

I used a DSLR (Nikon D3000) on macro mode (the shutterspeed set itself to about 1/50) with a 2-stop neutral density filter. I think I was also shooting in the direction of the sun, but as you can see it's not in the shot. What made the picture come out like this, and how can I get this effect again? Was it an accident, or is there a specific technique or angle that you need to shoot at to get this kind of lighting/color?
Thanks in advance!

Added (1). Sorry, I guess my question wasn't clear. I'm not talking about the focus of the picture at all, just the lighting and the colors. Everything looks slightly desaturated without being blown out. I almost think it's mainly the shadows that create the effect--they seem like they should be a darker color, but they look under exposed (not sure if that's the right word).

Added (2). I forgot that I had the filter on until I came back inside, but the pictures turned out fine.

Your camera focused on the flower… DUH

There was probably frost on your filter.

You can get a similar effect by breathing on the lens, making it fog up for one or two shots

Why did you think you needed a and filter? Shooting hand held, usually requires a faster shutter speed, not a slower one

You answered your own question. You shot into the sun (but not directly). Looks like there might have been some condensation on the lens too, which would add to the softness.

It's not under exposed, it's slightly over exposed, but it's a nice shot nevertheless.