Luggage allowance.

We got a shock this morning.After packing our cases we found that both were a bit over the 15 kilos allowed.With a bit of juggling,we managed to re-organise and transfer some items to our hand luggage(5 kilos each).The last time we travelled the luggage allowance was 20 kilos not including hand luggage.Quite a difference.Has anyone had problems at the check in desks with overweight luggage?We are flying from Glasgow Intl.