Sounds not likely from the dead rat, though the fact that it exploded means it was spoiled & may have had a build up of gases in the GI tract as it was nonetheless
swallowed.Sounds made by your snake when moving around, during or after swallowing do bear further surveillance though: it's possible that he is coming
down with an RI, but it's also possibly the result of some water (or other debris, like old shed) in his is nose or throat that results in "whistling" when he breathes.
I would find another source of rodents from now on...either that, or you need to review proper thawing of all rodents to prevent such spoilage. This subject comes
up all the time here, as many still think it's fine (or faster) to thaw rodents in warm/hot water, or by leaving them sit out for extended periods of time to thaw. Many
snakes will refuse to even consume spoiled rodents in the first place, because they have a very good sense of smell.