AINP sometimes asks for recent paystubs to make sure that you still have valid H1-B status. There may be a problem if AINP finds that you have changed your job by looking at your paystubs (your case may be delayed if they start questioning about your application and asking for more documents, or failure in updating AINP about your application may lead to rejection, like bendjoe mentioned). It is better to notify them any changes as soon as possible.