Do you happen to have a 2-roll tank? Or were these 120/220 rolls?
I have found that by using stainless reels and tanks rather than plastic ones, I have less contamination. I have used the same tanks for b/w and color(c-41) at school, just giving them a good scrub with HOT water after to make sure they're totally clean of residual chemistry, especially stabilizer/photo flo.
We have never, ever got any problems with stabilizer residues in reels. We have never brushed them, just normally rinsed with warm water immediately after processing. If you rinsed the reels, I would suspect other possibilities, too. If you didn't rinse them at all then it's a completely different story.......
I'm just a little weird in that regard, I like my stuff spick and span, if you get my drift .
I use a Jobo tank from time to time as well, stainless tanks usually though. If I shoot a roll of 220, my only option is using a Jobo reel, hence, why I have them.
a thorough rinsing should take care of it though, with warm water, right after your stabilizer step