Hi Mark,it is obvious you love your audis,I have just bought the A3 saloon 1.5tfsi sport and after 3 weeks I am loving it,I also have a passat but the audi is just edging it for me,so far so good ,good to read your post Dave Wise
Could be nothing ,but you could change oilif its not been done for a while or possibly check alternator belt ,if you can't find anything try a specialist garage to have a listen,good luck Dave Wise