common enough. depends on the type of lag. does it stutter? or just not react? Either way a map will sort it but it could be plugs or igniter. I'd pull out the plugs and see if they're dirty. Maybe change the air filter if that's old. There's always a chance that it's just a bit slow to react as it hasn't been driven much recently.

What's your setup? what turbo, injectors, ecu, etc?