Those seals can be installed by pushing them in with a thumb. They are not a true press- fit like the olden days but instead seal on the outside of the seal body itself, into the wheel's seal pocket with small rubber ribs (Easy Girls!). Because they are so easy to install and remove, I would not worry in the least about popping one out when man- handling the wheel around over a center post. I would put it back in and forget about it until the next time it is inspected while replacing the tire, etc.
Yep, cold tires are seriously stiff and difficult to mount (Boys!). Rotary mounting / dismounting levers are great but they do not bring the force to the tire in the best possible direction as tire irons do. Personally, I find modern tire irons so nice and easy to use I do not even bother with true tire levers and just use three irons to mount / dismount my tires while they are held on the tire machine (it raises the wheel up where it is easy to work on and holds it securely).
Brian
A few days ago I replaced my PR4 GT front tire in ambient temperature of 45 F. (BTW, I got 13,000 miles out of it) I replaced it with a Bridgestone T30 GT. I know from experience it is hard to mount the GT type tires and also hard to mount any tire when it is cold out. I warmed up the new tire by storing it in the house and I warmed up the old tire and wheel with a space heater in the utility room outside. I used a NO MAR to dismount the old tire and when I positioned the center post in the wheel bearing the bearing seal popped out! There was plenty of grease inside and I made sure there was not dirt or grit and just pushed the seal back in place and continued. It was however extremely difficult to mount the top bead. I was working the mount bar with so much force it kept popping out. I finally removed the wheel from the NO MAR and did it the old fashioned way with tire irons and my knees. I removed my new EBC rotor as I was afraid I would slip and wreck it. Finally got it mounted and a test ride proved all is well. Of course I am concerned about the wheel bearings and have order a new set from All Balls Racing.
I am wondering if the sudden temperature change caused the bearing seal to pop out. The 08 now has 133,000 miles and I have probably changed 15 front tires on it and this has never happened before.