I would change the pulleys too, if not the seals. When I did my timing belt I fully expected to see my old tensioner had begun to leak. There was a loud rattle for the first few minutes at cold start, so I figured the tensioner was leaking and allowing slack in the timing belt. But when I took the old tensioner out, it had no signs of leaks, and still tested good. I could tell the belt was slipping on the idler and adjuster pulleys though because they had dark black streaks on them. Since there wasn't anything obviously wrong with the tensioner, I assume the pulley bearings were going bad because when I opened them up there was a surprising lack of grease inside, and what grease was there was mostly dried up and flakey. I changed the tensioner, and both pulleys, and the noise is gone since then. So, in the end, what I'm saying is don't just assume the tensioner is the problem, and if I were you I would change the pulleys.