Hi, I just got my new 55-250 IS lens, very excited about that. However, doing my initial experimental shots, I heard a distinct whirring noise from the lens whenever the IS function was switched on. (mounted on my EOS 350D) Has anyone experienced something similar ? I wonder, if its a universal thing with that lens (because I didnt find anything like that in any reviews I read before ordering that)... or I just got a bad piece ? cheers raghav..