That "new car smell" is caused, more specifically, by the leaching and evaporation of plasticizer (this is the glue that holds together plastic, anddd gives it its rubbery characteristics - so more plasticizer = more flexible = softer = good for depressing impact... etc.) This leaching isn't really a big deal for the product in general. I'm not really sure why it makes you tear up. I haven't really experienced this at work, and I work with PVC every day.
An interesting thought though - when PVC is first made, there is about a 24 hour period that follows in which the pvc continues to set up and becomes harder and harder. Once this period ends, it will typically stay around the same hardness level for the life of the product... Though, when cheap plasticizers are used - too much "secondary" plasticizer - the product will continue to leach as i talked about before. Leaching = less plasticizer remains in the product = the plastic gets harder.
I wonder if your shorts will actually lose some of their softness/impact resistance as this happens and if the plastic in them will eventually become more stiff.
I doubt it would ever make a huge difference. I was more just thinking out loud.
Sorry if i lost some of you guys, but this was right up my alley
Chemical Engineering FTW!