elevated bilirubin

My husband is 62. He has one cardiac stent in his LAD and has been on heart meds for several years.  He takes Altace, Coreg cr, Lipitor, Plavix and Flomax, aspirin. Last month he performed well on a nuclear stress test, but his lab values for bilirubin were slightly elevated(104). The test was repeated and the result was 105.  He is overweight but exercises fairly regularly and is very active.  His cholesterol levels are within normal limits after trying several different
meds several years ago.  Whatwould cause this and should we be concerned? Thanks.