Smoke from Crankcase Vent

[MatC #5708]

After sitting for a while (the bike, not me), I restarted my 79 CBX with 15000 miles. It has individual K&N filters, so the stock air box is gone and the crank case vent is now just routed to the bottom end of the frame below the battery box. Now, I see more smoke than I remember seeing before coming out of the vent. Does that mean I have a piston ring leaking or a bad valve seal? How can I really tell?