Should i be mad?

So my fiancee and his ex wife has a child together and recently their child has had some issues which has caused them to ride together 2 hrs away..Which i haven't said nothing and has been understanding..idc that they ride together to tend to their child, but when i call him he doesn't talk really.. Or he will say oh its bad reception..and the phone hangs up and he never calls back ..... But under different circumstances he ALWAYS call right back ...bad reception or whatever....i feel as if hes intentionally not calling or not being himself around her ....should i be mad?