Legs not aching after hardest session. Overtrained?

I remember one gentleman saying that if the legs dont ache after a hard ride, then you're overtrained. However, I've only been riding 4 times a week since school has started. I have substituted my normal rides for racing roadies on a philadelphia bike-way. Man, what a blast. You guys get so irritated! Thanks

 

I actually thought it was the other way around. If your legs DO ache, then you've overused them (though you're doing them good by doing so). ...but if they don't, you can stretch 'em out some more.