If my engine is cold and I start driving, towards the end of 1st gear, i hear a fluttering sound. It disappears when it shifts to 2nd though.

I changed my air filter right before this started happening, so I think it might be that? It does it the first minute or two after I start up my engine, and it only does it around 2k RPM in 1st, then stops right when 2nd gear engages.

It's the first time i've ever changed the air filter so i'm not used to the sound, but it makes sense that the engine is pulling air harder towards the end of the gear.

tl;dr - is it because of a new air filter?