My bike's rpms run at about 3000 for a good minute after I get off the highway.  They then fall to about 1500 rpm which is where my bike normally runs.  This is a new problem for me, I was just wondering what kind of problems it could be.  I plan on getting new spark plugs for it and seeing if that helps.  Any other advice?

drop your idle a tiny amount?

is the choke all the way closed?

See this thread for possible solutions to the "hanging idle" problem:
http://gstwins.com/gsboard/index.php?topic=41199.0

I have the same problem - new sparkplugs yesterday so thats not it. 

If I have it in 1st gear and let out the clutch slightly at a light, itll drop the RPMs back to normal.  Hmmmmmm

The problem you are both describing is called a "hanging idle". Read the thread I linked above for a troubleshooting checklist ; that thread is "sticky", which tells you that hanging idle is a common issue.

The bike can be very sensitive to the idle setting, so make sure to set it (1200 rpm +/- 100 rpm) when the bike is fully warmed - this means idle until it needs no choke and then ride for about 10 minutes. If the problem happens while riding, pull over and set the idle then.

You adjust the idle by turning the big brass screw that hangs down between the two carbs.