I have a 4-5 year old speckled and he always makes strange little huffing and puffing sounds. These range from "meeps" to sneeze like sounds to just puffs of air that remind me of an irriatated grunt. From talking to others with speckled hogs (there arn't that many of us), this seems to be normal behavior. Mine is without a doubt the noisiest snake I have ever had!
Jim
P.S. Here is a photo of mine. I just love showing him off.

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1.2 Western Hognose Snakes
1.0 Malagasy Speckled Hognose Snake
1.1.1 Bearded Dragons
1.0 Green Iguana
1.1 Cats
0.1 Dog
1.0 Rat