Had a search, but the one I'd half-remembered turned out to be the usual case of someone putting in heavy-duty springs. The other popular cause is down to improper adjustment of the cable and the actuator in the sprocket cover.
How worn was the actuator? I had to replace the bearings in mine… it's possible that might be giving you a variable take-up point if your balls aren't spherical.
There is probably a slight variation in take-up point as the bike goes from cold to hot. It looks, from the drawings as though the position of the clutch itself is fixed to the right hand side of the crank case. This means it'll move away from the pushrod slightly due to the difference in thermal expansion coefficients of aluminium alloy and steel. But, it will be 0.25 mm maximum which is still well within the range of pushrod movement available… otherwise we'd all have the same problem.