Apart from other factors that have already been discussed here, do you live in an area where there is a lot of humidity?
Be sure you are not causing the problem by smoking you pipe too fast. That creates moisture and causes the pipe to smoke hot and can lead to moisture build up.
A variety of factors can cause gurgling, structural issues, like the aforementioned turbulence, moisture level of the blend, shape of the pipe, operator error etc.Some of my pipes need a cleaner to soak up the bubbling moist mid-bowl, while others stay dry for two bowls back to back. Maybe coincedentally, the dry ones tend to be more expensive, so what is it? the curing? Or some specific characteristics of the briar?