Yes, you are entitled to the profit. Your situation will actually be pretty much the same as those of us facing shortfalls. You need to make sure that all the charges made by the lender are justified. This site will give you more information.(posted 8332 days ago)Does your lender know where you are in the USA? If not, then write to them at their head office, give the mortgage account number and property address, and ask for a completion statement. Then take it from there.
Do read through this website. Just because the house sale made a profit doesn't mean that the lender can still skim off the top with unreasonable charges.
How much you want to pursue the matter is up to you. If you know that you can get £20,000 out of it and you're happy with that, then its up to you, but if you find out that it could have been more, or the amount being charged in fees greatly reduces this profit, then its certainly worth pursuing.
Good luck.