hmm... hold the phone. seems I use this bit of code to shorten the RSS cache time. could be the culprit as well
//shorted cache feed time
add_filter( 'wp_feed_cache_transient_lifetime', create_function('$a', 'return 50;') );EDIT: yup that's it. I guess I'll just remove this from my functions and deal with the default cache time.
EDIT2: now it doesn't work with W3 Total Cache 0.9.2.8 enabled. Seems like there's some screwy stuff happening with the RSS in the 1.4.4. interested if anyone can confirm this.