Bottom line, if your making payments on time, the bank really wont bother you.
First, if you signed a form when you purchased the home that expressed your intent was to keep the home as your "primary residence" then it needs to remain so until after your loan comes to fruition in the time you described.
One question comes to mind though, I have not in my experience ever seen a letter of in tent to occupy with a timeline.
Are you sure you're not talking about a pre-payment penalty for refinancing your mortgage?
Now, if you got a job out of state you could rent for a while until you purchased another home but do that after you sell yours.
The likely hood the lender might find out is higher if you post questions on the Internet asking if it's alright.
All The Best,