Specific to your query.
1. UAV movement along either side of LC with intermittent cross over, was routine till sometime back.
2. Usually the UAV movements take place at night, and are at times, difficult to detect with a naked human eye as there are no navigation lights on in such moves.
3. Before someone brings in the 'Radars', most UAV's usually move along the valley contours and are difficult to detect by Radars due to topographical interference.
4. No MANPAD engagement of MALE/HALE UAV has been undertaken till date, by either side, as far as I know. That is a step up on the escalatory ladder, which neither side wants (then the Helicopters, technically not allowed within 5 kms of LC, will be targeted, which are needed to undertake the relief/replenishment/recon sorties).
5. UAVs need not cross the LC to keep an eye on movement if altitude adjustment is appropriately made. The strike team went a couple of thousand meters deep which can be tracked by an on station UAV easily.
6. Pertinent to note, an Israeli team was there to provide technical support in the run up to and execution of the actual operation, to ensure no 'technical' glitches occurred hampering the real time situational awareness for both the political and military leadership. After all, their equipment was being used in a very critical operation and the smoothness of operations of their equipment was an important aspect.