A B767-300 First Officer reported encountering wake turbulence shortly after takeoff at their international departure airport; complicated by an abnormal gear door indication. Cycling the gear solved the indication problem and they continued.

Narrative

I was the flying pilot; performing reduced thrust; flaps 5; ICAO procedure takeoff. We had minimal spacing for takeoff behind an A320. Winds straight down the runway. During normal ICAO encountered mild wake turbulence from preceding aircraft. Retracted gear at the normal point. Approaching 1;300 FT AGL received master caution aural warning. I remained fully engaged flying the aircraft on the ICAO climb schedule; dealing with wake turbulence and the altitude restriction. A quick glance provided a gear door light with all three gear lights indicating black; not down and locked; which matched the handle position. I noted the need to monitor speed for gear door limits. While I flew; the Captain and [Relief Pilot] commented the condition and the Captain put the gear handle down noting the gear door indication. Upon normal cycling time the gear indicated 3 green gear lights with no other warnings or indications of problems. The Captain then raised the gear handle; a normal retraction occurred. We referenced the associated checklists; determined we were in a normal condition; continued on to destination.