Hecarim and the Explorer Mastery

For the new mastery "Explorer", this gives you +12 (now +15 on 5.24) Movement Speed in the Brush and the River. Hecarim's Passive increases attack damage on Bonus Movement Speed. I noticed that Hecarim's passive does not trigger with explorer. In my opinion, Hecarim's Passive Attack Damage should see that 5 or so damage increase while standing in the brush or the river, and it's not. His passive does NOT see an affect with the explorer mastery. I think this could be confusing a lot of Hecarim players that would be expecting to receive that bonus. Just wanted to let Riot know. Also, I noticed the +15 does not scale with any % movement speed items either, I would think if you had a tri force and move speed quints for instance, that increase in speed should actually be +16 or 17, not simply +15 while in the brush or the river.