Dog sneezing whenever attention is given?

[Mutts say: Don't Litter!]

This is a weird question...but we have a dog at work who whenever you give him some loving it's like he comes down with a sneezing fit. He has been like this as long as I've known him (3 months). He has no sign of illness and won't sneeze when you're in the kennel (so I know it's not like he sneezes all the time) but only when you're patting him. Anyone know what that could be a result of?

This is the same dog that I asked a question about a couple months ago, a fear aggressive dog who somehow is still hanging on with us, even though he's not available for adoption. His name is Arlo. It couldn't have anything to do with fear aggression could it? (I know that's a silly assumption, but it's just weird how much he sneezes)