If they're just little cuts in the heels and cuffs of your pants, don't worry about it - it happens, whether you're falling on rails, hitting hard snow, or clipping them into your bindings - it happens.
If they're bad and you want to do something about it, yes, you can duct tape them, but I feel like that would look shitty on basically new pants. What you should do (and remember, this is if they're bad) is take duct tape, tape it from the inside (yes, this will require work, because you'll need to get the duct tape inside the outer lining of the pants - that's what tore) and seal it; then sew it up. I did that on my pants and haven't had a problem with the big ol' rip I had since. It'll take some time, but its worth it.
In the meantime, just make sure you're not clipping your pants into your bindings. If you want and you think its legit, you could go Ian Compton steeze with the pant cuffs rolled up - I do that at rail jams.
Eventually you'll find what works best for you. Good luck!
Someone once told me that by pulling up your pants/buying that right size of pant will help to eliminate most of those tiny cuts from the pant leg getting stuck between your boot and binding. He must have been joking though, that would never work in a million years.