Before you had the MRI, did you wear plugs and ear muffs often? I have read this theory that people who use earplugs regularly have higher auditory gain (and higher hearing sensitivity).

But still, if you were wearing protection during the MRI, that means that the sounds that reached you were on par with your usual baseline sensitivity.

Years ago, I remember getting tinnitus from listening to loud music through earphones and attending concerts but it subsides after 1 or 2 days.