Calipher housing bolt

[Daddybluwagon]

Its weird one of my calipher housing bolts came out and I don't know how and I'm hearing like a tapping noise whenever I'm close to a wall. Now I know its hard for anyone to admit to making a mistake, but I'm sure its nothing I've done myself, I always double check my work, so tell me what you think it is.

 

[redpr5]

caliper.
as far as tapping, wheres it coming from? if its from the engine bay, it could be either valve tick or a rod knock (hopefully not a rod knock). or something else. idk. but i know i heard tapping when i was next to a wall when i had my rod knock