Noise from rear windshield after "regular" service

Yo yo.

So I brought in my beautiful baby for an oil change and figured might as well do their service while I'm at it. Car was working PERFECTLY.

Now I hear this noise from rear (I think windshield) like a fingernail from a girl with those long fake nails ticking, ticking, ticking, kinda annoying!

I`m going to hope the mechanic can fix this mess, but if not, what is to be expected? Should I demand my money back?

What could they have possibly been checking back there that caused this problem?

Much thanks!