Hello There!
This is called a "PARADOX"
It is a statement that appears to be self-contradictory or silly, but which may include a latent truth.
Yes, it seems to be an alternative, in some situations acceptable, but eccentric and not neutral spelling of this word. It accents the fact that "ea" here are two separate vowels rather than a diphthong: that is the function of the trema (the two dots).
In practice it's not used much, because it's not really necessary: it does not distinguish it from any other word, and trema is not easy to find on English keyboards: so there is no need.
"I walked into the kitchen,highly irritated"
