Doesn't sound like a *bad* thing but I'm a little perplexed. Normally, I work a given muscle group to failure on the last set and - until recently - could feel some stiffness/soreness that evening and the next morning. Lately, though, I still work to failure but don't "feel the burn" later on.
The only thing I'm doing differently is that I've switched from mostly free-weights to using one of those Weider pulley-machines-of-death units.

My routines are basically the same and, if anything, I've marginally increased the weight I'm lifting. My diet hasn't changed and I'm not doing any type of new warm-down. So what's going on here?
Thanks,
Keith C.