Concered about seam/ridge in shower tray

[ElleR]

Got a new bathroom last month. Noticed on Friday that there's a ridge/seam appeared in the shower tray. Picture is best I could take of it but concerned this could turn into a crack?
Going to message plumber tomorrow but wanted to ask here in case any advice or thoughts on what's cause it and if it is an issue

 

[Madrab]

Cant really see what's going on there but if something that wasn't there and is now then no reason not to get him in to take a look.