He also apparently didn’t anticipate that anyone would notice. But on 19 Apr 1952 the author of those stories sent this letter to the company:
Just a note to remind you of an oversight. You have not as of yet sent on the check for $50.00 to cover the use of secondary rights on my two stories THE ROCKET MAN and KALEIDOSCOPE which appeared in your WEIRD-FANTASY May-June '52, #13, with the cover-all title of HOME TO STAY. I feel this was probably overlooked in the general confusion of office-work, and look forward to your payment in the near future. My very best wishes to you.In a postscript, Bradbury recommended that the editor check out his books for more stories, and even offered to send copies. No doubt pleased not to be facing a lawsuit for copyright infringement (Weird Fantasy, #12, had also contained a story inspired by one of Bradbury’s), EC paid the suggested fee and did indeed license several further stories in advance, thus time trumpeting Bradbury’s name on its covers.
That letter is reproduced in Grant Geissman’s Foul Play!: The Art and Artists of the Notorious 1950s E.C. Comics. Check out Histories of Things to Come for a peek at those stories.