LA Roofing: Not Above Reproach?

I tend to think that LA Roofing exaggerated the need for our roof to be replaced. So far two different people have told me that even in the case where narrow crown staples (better to use broad crown staples or nails) have worked their way up to the top of the shingle, the asphalt shingles are self-sealing and will, in effect, seal any penetration caused by the staples. The roof is only 13 years old and not every staple is showing. There are some diagonal lines of staples showing on the roof. I stood on the ladder while LA Roofing was here and even commented to them that I could see large numbers of shingles that did not have the tell-tale black line of the staple head. The owner also acted like that was what was causing the leak around the furnace exhaust vent and that it was imperative to replace the roof ASAP. When I asked when I might have a problem if I didn't, he gave no further elucidation. I think the reason he lit up a cigarette and smoked in my face, without asking if I minded, is that he's stressed when he tries to convince a potential customer that 1+1=3!!