“We’ve analysed their attack sir, and there is a danger” is consistent with the unpredictability and audaciousness of the Rebels’ hastily conceived plan. Otherwise the dialogue would/should be “Governor Tarkin, we’ve been betrayed! A design flaw was deliberately planted in the station and we must evacuate immediately!”…
Or in the midst of a battle… Bast (and his team) analyzing what the Rebels are trying to accomplish with their small fighter attack… immediately reports the newly found perceived danger to his superior. Likely further analysis on the how, the why, and by whom - with any likelihood of determining intentional sabotage in the design of the Death Star systems is probably ongoing (or hasn’t yet finished formulating the information). Seems logical enough.
There is an arrogance, complacency, supremacy or overconfidence on display from the Imperials through the OT, afterall.