Dirk-
Hey, sorry didn't respond sooner-been out of town. You've already figured it out, but I'll add this to back you up-I've had mine in below-zero temps and no issues with any of the lines. What I did notice was that in large temp variances from hot-cold or cold-hot, that temp difference would cause the compressor to kick on a bit to even things out. Other than that, no issues. I just pulled my air fittings though and will be removing my compressor setup here shortly. Planning on changing things up before to long and gaining a little more clearance in a few areas.
Hope you had a great holiday.
Best of Luck,
Mike