Mucus can be a sign of intestinal distress and/or bacterial overgrowth. It would make some sense that he would have a bit after recovering from an ileus event, but a lot would not be a good sign. If it keeps up, he may need vet reassesment. It's good that you gave him Bene-Bac before--maybe another dose would be good.
an increase of good gut flora with a probiotic,,may have caused an unbalance of gut flora resulting in bacterial overgrowth-(mucus)... good intentions sometimes have reprisals.....sincerely james waller,,antibiotics and probiotics..ie.house of rabbits