My Panasonic did the same. I just used the heat another way. Set up fans to blow it around. It got a great picture too, but you did not want to leave it on while nobody was watching.
The Panasonic plasma picture is still great and the TV must be 15 years old now. It was our first flat screen TV after retiring our 20 year old conventional 27 inch Sony Trinitron which had a great picture, too. We’ve been here since 1983 and have had only two televisions! I had one small repair done on the plasma TV maybe six or seven years ago.
That is really remarkable.