Identification Help Please

Can anyone ID this bird I saw February 19, 2018 at Big Cypress Bend Boardwalk in Collier County Florida. I saw it simply sitting and preening in a low tree in the swampy area along the boardwalk. The bird is about the size of a blue gray gnatcatcher but the distinct white cheek patch is something I have not seen before. If you are unfamiliar with the area, it is about 75 miles due west of Miami, Florida, USA

 

Thanks in advance to anyone who can ID this little guy for me.

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