Assume nothing, and it's not uncommon for electrical panels in basements to see water infiltration via the outside service itself, as the cable/conduit from the meter to the panel also can direct water. Moving the panel to discover the source of the leak involves opening it, which you shouldn't do unless qualified - but that will at least let you know if the water is coming from the panel or from the wall behind it.

I have a slight leak when it rains behind my breaker panel. I assume a crack in the foundation or similar issue. Panel is attached to partical board and it is crumbling. What can I do? Can the panel be moved enough to see the leak source? Any recommendations? Thanks!

Foundation leak behind breaker panel