Wet drywall around newly installed bathroom window

Had an old, dry rot wooden window in the bathroom which my contractor replaced in this 1950s apartment. I have good ventilation with the fan but during the heavy rains the past week I am noticing wet, soft spackle or drywall in the corners. I'm having the contractor come out next week to take a look and he believes it's perhaps the silicone seal that needs to be redone on the outside. Is there anything else I should consider or anything else it could be? He did install an exhaust for the bathroom fan above that window as well.

https://imgur.com/a/EPcWYJz