We live in MN, in a house built in 2008 (and our water heater, installed in the basement, is about that vintage).
For the past few weeks, I'm detecting a smoky smell from the hot water out of a 2nd-floor shower. I don't think any other hot water outlets show this (as far as I'm aware now).
This typically happens after a couple of minutes into a shower, and lasts as long as the hot water runs. The smell can best be described as an old-timey campfire, with all the smoky smell but none of the actual smoke. There's no sulfurous or other similar "bad" smell... if anything, this is a very comfortable, let-me-stand-here-for-another-hour-and-feel-cozy kind of smell.
The water heater is your average run-of-the-mill gas-fired unit, and I haven't done any preventive maintenance to it in the past six years. Not broken, so never had to fix anything.
What could cause this out-of-place smell in a relatively new house?