I've noticed this stuff tends to dry out and get harder/less tacky over time.
Store the extra in an old film canister or zip lock bag.
I always have to work mine for a few minutes in my hand before using it after it's been stored all summer.
My worry with it would be creating a small hump in the track with it's use.
Once the cat gets done moving the connected Uni Track around the layout board so it isn't parallel to the edges I'll probably use the cheap caulk method to prevent further realignments by the kitty.