(Salem, OR)  --  Governor John Kitzhaber says he's "concerned" with the limits on the amount of marijuana an Oregon resident will be allowed to possess at home.  The voter-approved Measure 91 would allow residents 21 and older to possess up to a half-pound of pot at home but only one ounce in public.  The governor says the amount that's allowed to be grown at home appears to exceed the amount someone is allowed to have legally and would be difficult to enforce.  Kitzhaber says he'll send the Oregon Liquor Commission a letter that outlines his general principles regarding marijuana regulation.