Rengar Q

So ever since the change I taught rengar's normal Q would no longer give attack speed buff, but I noticed when playing him, when I activate q regardless of being ferocity bonus or not, it gives a small attack speed buff of about 10-15% for about 1 - 1.5 secs, can't really tell any of the numbers, but is this a bug or intentional?

Edit: So I checked the game again, his normal attack speed is 0.68 and it rises to 0.95 upon activating his q, now looking at it, the buff last more than it's q duration about 4 seconds

Edit 2: Upon actually triggering the q on an enemy champ, minion or monster, the duration only lasts for about 1 sec or until next basic attack