Pixhawk F450 Not Straight

I’ve built my first drone, with an Pixhawk 2.4.8 on a F450 frame. I had a flight with it, in stabilized and it had some drift away, not much. Now, months after, as the weather it’s getting a bit warmer, I want to fly it again. The thing is that if I place a buble spirit level between each arm, they are not parallel to the ground. Does that affect it? Also, I’m kinda scared to put it in loiter, alt hold or basically anything else rather than stabilized, what should I check, what should I know before?

Level the frame by packing under the landing gear so your bubble level shows nice and level in all directions, then press the Level Horizon button in QGC under the Setup/Sensors section.