Well, that woulda been nice if it wasn't. But, since I'd swear that's the same kinda noise... I would suggest looking into that primary, something is amiss.
Also, as a mechanic I get complaints of noises all the time...noises that can only be heard doing a specific thing (that is not normal driving) under specific situations (sticking your head under the car). What I mean to say, is if you can't hear that noise while cruising in top gear.. then it is most likely not an issue.