iPhone displaying the "completely charged" symbol when only charged 80%?

[helloimD4NNY]

Okay so since yesterday my iPhone has been displaying the "two prongs" when not completely charged. I have read on here that the two prongs is a symbol that the iPhone is completely charge, yet my phone shows that when my battery on the lock screen shows that it's only 80% charged.

My question to you is: Is that normal?

 

[rogue0wn]

This happens when you iPhone is over heating. Let it cool down a bit and it should charge fine.