If I recall precisely, we have to specification of the reason Gandalf first visited Moria. So maybe he was sent by Saruman, or the White Council as a whole, to investigate that very matter.
Saruman's clearly someone whom likes the comfort of Rivendell, Minas Tirith and then Orthanc and Radagast is going native west of Mirkwood so Gandalf is the logical choice to go investigate.
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Head of the Fifth Order of the Istari
Tenure: Fourth Age(Year 1) - Present
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