Crack in mortar?

[NewShoes]

Hi all, just was looking up at my roofline tonight and noticed this cracking on the mortar (right hand side, above the window). I'm not sure if this is a new crack, not having noticed it before. I've recently had the roofline cladded in uPVC and wondered if it was this expanding etc that could have caused it, or is that unlikely?

Cheers

 

[noseall]

End brick. Very little lateral restraint. Silicone pulled on it when curing. Pop!

 

[NewShoes]

Thanks, is it an issue or best to just to get up there and pop some clear LMN silicone in it?

It looks like there's also a fine crack in the mortar on the next brick along

 

[noseall]

pop some clear LMN silicone in it?