Jeff,
this seems totally random, could it be that non-greedy regexps in tcl are not quite reliable. I remember having a problem getting them to work once and couldn't track down what the reason was. Seems like the non-greediness of the white-space quantifier carries over on the quantifier between the tags. I experimented and noticed that it's ok to have a non-greedy quantifier after the tag, but not before, regardless of whether it's whitespace or not.
