P1273 after having the following mods done: (have cleared the code a couple of times with OBD2 but it comes back)
mods: Stillen Hi-Flow Intake with Z-Tube
Motordyne ART Pipes & Shockwave TDX2 Exhaust
Dyno Tune (Osiris)

1. did a search and it looks like I need to try doing the mixture ratio self-learning which must be performed after replacing those sensors, once the engine is up to temp turn it off, unplug the MAF, turn it on and let it run for a minute, turn it off, plug back in the MAF, clear codes via OBD2, reset ECU either by OBD2 or pedal dance then let you're good to go and it will re-learn properly.

2. or should I contact the shop that did the work and let them deal with it?

car seems to be running great, I wasn't smart enough to see what my AFM is according to my OBD2...

 

If you didn't have the code before the shop did their work by all means take it back to them. More than likely what they did set off the light and IMHO it's their responsibility to find the issue and fix it.