Check Emissions

Hi guys

i have had my decat fitted for the past 3 months or so, where i have done over 2k miles, today only after a short trip to see my nan, i got the " check emissions " sign on the dash bored and the engine managment light on.

Is this normal, thought it would of come on sooner?
 
Perfctly normal.
I get it with decat too.
Will go away after about 10 small trips in the car.

Something to do with the ecu checking it's all ok.
Mine goes after a few days.