Not exactly sure what you mean. Is the trigger sticking in after it is pulled? Or is it kinda wonky as you are pulling it? It might be that something on the inside is impinging part of the trigger mechanism, but from what I have heard SP does impeccable work. Did it ever have this sticking issue before you sent it out? My first reaction would be to say maybe the inners have gunked up in some way.
Wanna post some pics, might help the diagnostic process?
Home defender, and Home brewer!
XDm-9 3.8 compact w/ PRP guts, Meprolight TruDots
KGP-161 Williams Firesights
Mossberg 500 12 gauge
Remington 11/87 Premier 20 gauge
Kimber Custom TLE II