Yes, there is a possibility of phosphoric acid residue in every type and brand of PEEK material (tubing and other PEEK manufactured items).

This is a known side effect from the manufacturing process, and it should be noted only on a few occasions PEEK parts may contain only a very small amount of phosphoric acid residue, which is washed away rapidly and will not last long, if at all. 

This small amount of phosphoric acid would most likely only briefly effect critical methods and not large scale/prep chromatography or chemistry.