Nope, hadn't heard of it ('til now, *gasp*), but Ira (who was neutered over 1 1/2 years ago) has made a few attempts to mount Mink (who is "coming of age"). They're not ever alone together because Mink is crated whenever I'm not right there, and I wouldn't be worried about a pregnancy considering that he's been fixed a pretty long time, but now that I know that they can get locked anyway, I'll watch them even closer. It'd be the last straw in this household full of running animals!
I'm glad you posted this... Are they both ok after their adventure in sexland? (Oh yeah, and so much for "fixed animals have no sex drive" - learn something new every day, huh?!)