Egyptian Walking Onions, Topsetting Onions

I've been growing these for about 8 years now - I just leave them to grow and harvest the bulbils for giving away, or for selling etc; and I've not encountered this before.


The tops are usually quite small, a few mm in diameter, sometimes a cm but this year, they are the size of shallots.

From this:

 

To this:

And this is also the year that I got garlic that did not split:

I usually note if something strange happens and this is it. 

We didn't have much frost last winter; can it be something as simple as frost that makes such a huge difference to our perennial crops? 

I shall eat some of the Walking Onions, I mean it's a bonus as usually they are not worth peeling let alone eating; and I'll sow one large and one small and see what happens. But I am liking this new style Walking Onion alot.