basically it will depend on the shop. They should all have records of sales, but some shops ill be better than others. Also, if the shop knows you, you chances are better. Hell, if you have good ties to a shop, sometimes they'll even warranty something you bought at another shop.
Go back to the shop that mounted your skis, they should have a dated shop receipt from the day you had your bindings taken care of, I'm sure Salomon will accept that as prooof that those binders are within thier warranty period.