I've developed two rolls of HP5+ today, and everything worked out well, except from one spiral being too old, thus... chewing film! Oh well, since the negs turned out fine and i've only lost three exposures of one film, i won't whine.
So, since i follow the same procedure every time, and everything works well, i think that the Tri-X negatives turned out overdeveloped at the lower 1/3 of each exposure because of that water tub accident. It's the only difference in that development, so i guess that it was the problem. Just in case anybody was wondering!