My Indy (who I trust) has told me twice now that the 07/08 Tourers with lowers have a TSB to remove them in hot weather. His are off, and he's not the type of guy to "just do it".
TSB is technical service bulletin. And no there is no tech tip or service bulletin instructing to remove the lowers in the summer. It is suggested in such literature as instruction sheets for lowers and whatnot, but no bulletin stating it specifically.