Not 100% sure, but the seals in every master cylinder i have ever seen are lip type seals, not O rings.
I agree with the other guys about the adjustment, back it off and bleed the system. A trick i use on brakes is after bleeding the system, tie the lever back to the bar and leave over night. This allows any air to rise up the pipe and out the top of the resivour. Should work on the clutch.
A link i lifted from another post http://www.jkhirst.co.uk/acatalog/Brake_Levers.html shows the type of seals fitted.