Dude, it is just time for service. If this is your first since buying your bike most dealers do it for free. There could be anything wrong from your cables streching a tad to just dust getting in the housing. This is probablly something you will have to get done alot if you ride alot. I probably get some kind of adjustment done monthly. Trying this yourself, although it will eventually build a valuable skill, will take quite a bit of trial and error and riding with poor drive train quality, and this can lead to you breaking a chain pretty easily.