It's not a prob with any strat I've ever seen. It's more an issue when the neck strap button is around the 15th or higher fret - like an SG for instance or maybe a tele, but my tele is 3.5 lb body, rosewood neck, and heavy tuners, and it's just fine for me.
Strats have that long upper horn, and usually a big hunk of metal as the bridge block. It might be an issue if your body is very light, you use a lightweight non-trem bridge, and have a heavy exotic neck and heavy tuners - like all-ebony with PW brand tuners. Also, the vintage modern necks are noticable lighter than the warmoth pro construction necks. I think if you get a big steel trem block like callaham sells, and lighter tuners, you wouldn't possibly have any problems.