My friend recently dumped upon me the task of taking care of his animals for the next 2 weeks while he's away in frickin' Hawaii on vacation. All seemed to be going well until today. It has been three days so far and none of the animals have any health problems as far as my knowledge. Today, the male burmese started gaping and hissing at random. It wasn't threatening or anything. It was opening its mouth and hissing like it was gagging-the thing that comes to my mind is like when a dog is trying to throw up. I've taken care of many snakes in my time, but this is new to me. In all, I saw him do this three times and heard it on at least a dozen more occasions while in the reptile room. It all happened within about thirty minutes and the three times I saw it happen, occured within two. I went back there this afternoon, about five hours later, and all seemed well. He just stays coiled up on his hot spot.
The snake has been a bit irritable lately, though. He hissed a lot when I took him out to clean the cage, yesterday. He is generally very calm, only letting out low hisses when he is just being taken from the cage (previously lived in a run-down pet shop). I know he is getting eady to shed, but his behavior still seems off. Has anyone had an issue like this or could maybe tell me about it? I tried contacting my friend (the owner), but have been unable to get a hold of him. Should I be this worried, or is this just something to ignore?

