Things will happen, even after you have had the car for months things can and will happen. I think if it were my decision I would ask to see what melted and if in fact it was the
oil pressure line I wouldn't be to concerned. Replace it with a AN 3 braided line not more than $50 from a speed shop. I had the exact thing happen to my
oil pressure gauge about 5 years ago.
Replace the
oil with 10 40 or 10 30 and also change the oil filter to a motorcraft oil filter. I bet after you do that your oil pressure will settle around 55 or 60 PSI.
Clois