Taylor,
You had better see documentation of the sublease to avoid entering into the legal morass that a top lease may bring. You can then determine that the current lease is actually expired before entering into a new one. Weld County oil operations will take on a new complexion in the next 3 years so you may want to figure out what you want from your minerals and deal accordingly. Don’t allow the leasing companies to convince you that leasing is a retail business. It doesn’t have to be that way. Get proper value for your commitments of what you own. You have much to gain in the long run if you are in the development fairway and careful to get what you want.