Can you post a pic of his tail? Lost of folks here with veterinary degrees and experience.. might be able to tell you if you need to take your snake to the vet ASAP, or if it looks okie.
When I worked at the vets office, there was only one snake we ever saw, and we saw it because of an incomplete shed of the tail, and by the time we saw it 1.5 - 2 inches of its tail was dead and the flesh had begun to rot, we had to surgically remove most of its tail (fortunately it was female, or else the hemipenes would have been amputated as well =/). It lived, and is quite healthy now, but if we had seen it earlier we wouldn't have had to do such a drastic surgery! (Not trying to scare anyone hehe, just pointing it out.. dead flesh tends to spred its nice like bacteriums to healthy flesh rather quickly ~,~)