Is my car okay or am I paranoid?

Recently, I have gotten 3 repairs on my 2011 Nissan Sentra to replace misfired spark plugs as well as the air filter and sensor after driving in a huge storm. The mechanic I've gone to have been super accommodating as this is my first car and my first semester in college. Though after I got my car back last week, i've noticed the gas and brake are way more sensitive than they usually are. If I even slightly tap on the gas it pulls forward and is kinda rough to accelerate. I called my mechanic just to ask if it was normal and he told me if the check engine light wasn't on then I shouldn't be worried. I feel as if I might be paranoid because the car died at an intersection and I want to make sure everything is fine before I take it outside of my town. My boyfriend offered for his mechanic to look at it on the other side of the state but in the meantime, is this normal and the engine is just running a bit smoother or is there something actually wrong? Thanks for reading