FYI... I have heard weird things off my bike also.. heard a really weird rattle noise last weekend riding, sounded like my engine was falling apart.. come to find out it was a loose heat shield plate.. Anyway if you have done your maintanence the way you should so there are no real worries with the motor, just go over the bike and check bolts and screws things like that. Hope that helps a little.
Deathbringer
(The Corporation)
2002 Yellow 400ex
Armadillo Chrome Bumper
WB E-series pipe
WB Rev box
Dyno Jet kit
K&N filtering/moded airbox
Chromed headers
Lots of bling bling