The last tube pillowcase I just made is not quite right and I don't know what I'm doing wrong.

The case itself is fine, but when I sewed the second French seam and turned it right side out, there was fabric sticking out from the middle of the seam . Obviously I'm not lining something up right and I can't figure out what it is. I was very careful when lining up the 5 layers, pinning all along the way.

Anyone have a clue? Any help is appreciated. Thanks.

Renate