Stimulus Payment Arrived - I think. How did I get 90 cents?

[acgvme]

I received a direct deposit on April 15th with a description of "IRS TREAS 310, TAX REF" in the amount of $260.90.

How in the world did the government come up with a figure that ends in 90 cents? 

I already filed and received my 2019 tax return - it wasn't for this amount. I'm concerned I received someone else's tax refund. 

Any ideas?