I just made level 5 and I immediately noticed that my ability to get a portal key while hacking went down. Before, I was getting a portal key about 90% of the time (assuming I didn't already have one). Now it seems I get one only about 30% of the time. Everything I've read says that the probability of getting a portal key does not change with level, but that doesn't seem to be the case. Does anybody know what's going on?