Aqua Pex and Freezing

I just roughed an upstairs attic 1 zone heat. Have about 78 feet of BB the pex was run through 3 spaces that are under dormers where you have the soffet bringing in some attic air. Roof insulated and walls insulated in the attic construction. I insulated all the pex I'd say 30 feet of pex runs on the floor with 3/4 armourflex wrapped tightly. In other places the armourflex has fiberglass insulation wrapped around it. My concern is the contractor framed in and sheet-rocked the 3 dormers where i wanted to put more insulation around the armourflexed pex. But too late. the pex I am talking about is about 30 feet. Not near the soffett but little concerned whether I should get in there to use more insulation before the entire rooms are finished?
I'm confident but have some doubt. Have used heat pex in this type of situation with no problems but thought to throw it out there. What about antifreeze?