choking? eating too fast? illness?

[Ziggy]

Ok, rather long.

A long time ago, when my boy jack was a baby, he chewed my wall while I wasn't looking and inhaled some of the dust off the brick. He began making a horrible bubbling grunting noise, and really loud because of the stuff he'd inhaled. Imagine a rat eating a peice of dried pasta in a big echoey room. Kinda like that. Obviously I rushed him downstairs to see if the vets were still open. Throughout this all, Jack was FINE. He didn't even seem to notice what was going on! He was trying to wrestle with my hand, licking me and eating yoggies, all the time making this noise! In a matter of minutes, he had stopped. He was absolutely fine and back to normal.

A few nights ago, my black dumbo, seven, who is around 11 weeks old, suddenly began making the exact same noise. I got him out of his cage and sure enough, he was completely oblivious to everything and was trying to steal yogurt from me! Whatever it was, it clearly wasn't distressing him! In about 2 minutes, he'd stopped.

Had it been a one off, I'd put it down to him probably having bolted his food down too fast (it was just after I'd fed him) but then last night, he did it again.
Again, after being fed. This time it lasted about 4 minutes then he stopped completely.
He's never ever had any respiratory problems, never sneezed or anything. I'm very dubious as to whether this is any sort of respiratory thing since it was exactly the same noise jack made when he had inhaled something into his lungs.

Any ideas what this could be? Does he just bolt his food too quickly and not chew properly?