My '02 2500HD DuraMax has had an odd alternator issue since I bought it new in July 2002. At start-up the alt. gage takes approx. 1 minute to indicate full operation(14+from <12 VDC). The truck is now 5 yrs. old w/60k mi. It seems to have developed a new quirk in addition to the original one. Now even after full op. of the alt. the lights flicker noticeably for an add'l. minute. The belt has <10k mi. on it and is the correct length and tension. Is my alt. going to leave me stranded?