Buzzing noise after car sits for a few days

[MattB]

I took my car out for a drive today after it had sat for several days and been rained on quite a bit. As I started driving I noticed that the exhaust sounded kind of buzzy between 1.5-2K RPM or so, but once the engine started to warm up it went away and didn't return. Is this something I should be worried about or should I just put it down to the engine being cold and having sat for a few days?

[maxhopper]

It could be just that it sat for a few days. I would try to listen for a similar sound after the car had sat different periods of time. After a few days, it may have been lacking oil residue on rotating parts at start up.

[MattB]

It could be just that it sat for a few days. I would try to listen for a similar sound after the car had sat different periods of time. After a few days, it may have been lacking oil residue on rotating parts at start up.

I bet that's it actually. I took the car out for a drive just now (car had sat for several hours and was cold again) and it didn't make that noise.