Saddles and Bent Metal Rails Has anyone else had issues with bent (slow deformation over time) metal rails on the saddles they have used? I previously had three or four saddles that all ended up tilted over to one side and accordingly less comfortable than when they were new.  I have since switched to only carbon railed saddles and have not had any issues.  However, I am now wondering if it might have been a brand issue (I can't recall if the set of saddles in question was all from one manufacturer or not, but it's a possibility) or this has occurred with other riders. 

The head mechanic at my shop claimed it was "just me" and I do have an ugly stroke, but I am wondering if others out there have experienced this or if I should have been blaming the manufacturer.
I have not just had them bend I have had them fracture. 
I took my saddle to the shop thinking they would say "wow how did that happen" and the response I got was it happens all the time - that saddle is a few years old. 
Aluminum will fatigue - low end seats have a limited life. 
A steel or titanium seat does not suffer from fatigue (will not at nearly the level of aluminum). 
Carbon also is reported not to fatigue but I don't have any experience with carbon railed saddles. 
Inspect your rails on a regular basis for deformation or cracks. 
If you go out the back and land your bumm on the wheel because the rail fractured it gets a lot easier to spend $100 on a saddle.

I think the seat position was also a factor as I had the seat all the way back.  What that does is create a longer lever from the back of seat to where the rail is clamped.  I also put an offset seat post on the bike so I got what I consider a better clamp position.