Do you think given that, running a sprinkler in dry conditions in the future is a good option?
No, you would only be using up valuable water. It should be conserved during a drought, not just dumped on the ground.
Would it be best just to see how it behaves over the wet season given it had next to no rain during summer/autumn? (outside getting an Engineer etc to take a look). Cheers Handle.
I think this is a good course of action. It's reasonable and normal to expect some movement. If you think that the movement is getting beyond reasonable and normal then by all means get a pro in to look. At the very least it may put your mind at ease, and give you a reference frame for future movement about what is normal and what is abnormal.