Giant Anthem Rear brake hose abrasion

[Butterbean]

So quick q for those giant owners out there:..

 

My 2013 X1 has developed a funny thing, it's abraded the rear brake hose on the cable tie at the pivot fastening point... So, quick q, how tight should that cable tie be to avoid the rub? At the moment it was as tight as I could make it, so do I go for that again, which doesn't make sense, or should it be a bit looser to allow the movement some room..

 

Thanks!