i don't know of an existing one, but i don't think it would be too hard to create as long as you could reference a real one. i could give it a shot next time i get the chance - unfortunately the problem with random events is that you can never predict when you'll get your next one :P

hahaha too true xD
From what I can tell, the random event box is the same green as the default subeta color scheme, so could change depending on which color scheme you're using. Item to the left, text centered in the description box.
I feel like are the pieces are there, plus the scode reference, I'm gonna give it a shot

[edit] Tried it for

i just got a random event and the text isn't centered. that said, REs are built as tables, so the image and text are in two separate cells, which should allow you to center the text. this is the structure, if you were curious:

Random Event
	Random event text.

then the header ("sp-sub") is just styled with a 1px black border and a background color based on your current site theme, but of course you could style it however you want.