Clean it
Protect it with some rubber crap (like what you would use on sidewalls of tires perhaps?)
Bleach+Rubber=BAD...remember the tire burnout deal? yeah...
You CAN dilute it a bit and that would be fine for general cleaning...but save the strong stuff for another day.

Just wipe it off and put some proper rubber treatment on it and it should be fine..
It wouldn't hurt anyone to yearly clean out the gunk in their rubber parts...I did my trunk seal the other day...whew...what a gooey mess.