My civic has been running fine w/o any troubles. I took it to a shop that had a coupon for a cheap engine oil change. After picking up my vehicle I made a couple of stops then headed home. On my way home on the freeway the engine started to slip whenever I pressed on the accelerator. Also noticed a violent vibration when idling or at lower speeds.

Is there any common mistakes that the shop could have done while changing my oil?

Or is this purely coincidence and my transmission is starting to go?

Thank you for your input.