paid off card and score went down?

I get this email from Turbo:

Reno, you paid off an account
Your TransUnion credit report shows you paid off your WELLS FARGO account.
See where I stand
Well done. This is exactly the kind of thing that will raise your credit score and get you more options in the future. 
 
Keep on rocking,
The Turbo Team

 

Yet my score instantly went down when I paid of the credit card.  What the heck is going on here?Seems so counterproductive and contradictory.