Gear Change Query

I have an O3 WRX . I have noticed recently that its quite hard to change gears.
Its hard to Describe but its as if there a tight rubbery feel when engaging gears through neutral.
Any idea whether its a gearbox or a clutch Issue.
Any help would be greatly apprecaited.

When was the last time the oil was changed and what oil do you use?

Alan.

Does this happen all the time or when the engine is cold?