Even if there was an air bubble in the oil pipe, I'm not convinced that would cause the problem. The system should be able to self purge. For peace of mind you could add oil to your next fuel tank. You're effectively double-dozing as the autolube is a mechanical pump that works in tandem with throttle. It'll smoke a little, but at least you know it's lubed.
The overheat sensor (which triggers the buzzer) is located next to the sparkplugs. Check the wiring, etc. The buzzer itself is in the remote throttle. A loose or oxidised bullet connector could give intermittent problems.
Is that with or without VAT?