kind of coincidental but I had the same kind of problem on my `98 202 a few weeks ago.
The problem went away and I am not sure why, but what I did do is lubricate the locking pin for the fuel filler door with 303 rubber protectant. I sprayed lots of 303 around that fuel filler lock near the gas cap and it helped me

test to see if the noise is from the fuel filler door lock.