As mentioned below, it's VERY normal. Not only that but it always amazes me when I read that there are people out there who say things like "it could go next week" when discussing oil dripping from its exterior. If only you knew how simple that device is, you'ld know that external oil seapage is hardly a sign of "turbo failure" which ONLY happens IF the bearings fail, very rare on newer water cooled turbos on a well maintained engine, even at 148K miles.
Although rebuildable in the event that a bearing did fail or a front or rear turbine shaft oil seal failed internally (never externally), most people would replace them then rather than rebuild.