I shoulda done this in haiku, but lunch is almost ready...
I would think so, too, except the same error is consistent as I move from town to town. The iPhone changes the location as I move, but the temperature is always running 3-5 degrees F higher.
For instance, Yahoo Weather is reporting the temperature in the town where I live is 1 degree F warmer than my work location, so it is obviously running off of a different sensor. But they are both consistently just a few degrees high. This is true wherever I go in the area.
If I hadn't been noticing this consistently over the last couple of months, or so, I would think it was nothing. But it has been too consistent for too long a time to dismiss it as simple error.