Anything can happen in comics. Say you had an idea for a story where Aunt May became a herald of Galactus named Golden Oldie and she finds a planet of golden sponge cake with a creamy filling to satisfy Galactus' hunger. You could totally write that story for a comic - if someone hadn't already written it. You big plagiarist.
In 1984, Marvel Team-Up #137 presented a very special story that had Galactus did visit Earth and did make Aunt May into his latest herald, the gold-covered Golden Oldie. At the end of the story, it was revealed to be a dream, but the glory of Aunt May wielding the power cosmic can not be denied.