I came across this problem earlier in the year with T-Max 400 so it isn't purely ILFORD related; however it was at a time when I experienced issues with not sufficiently washing out 'Ilfotol' (a photo-flo equivalent) from the Jobo film reels. Another issue I've seen probably attributable to wetting agent are bubble marks on the negative.
Tom, interesting. Are you saying that if the film reels are not properly washed after a session then the next roll loaded onto it is at risk? When would these marks happen then?