Breathing propane while pregnant?

Yesterday, I got home from work and the knob of the gas stove had been bumped by my husband or I that morning. Propane gas had filled our apartment for the previous 10 hours. I immediately smelled it when I got in. I took about 3-5 minutes turning off the stove, opening windows and doors, and turning on all fans. I went outside for about 30 minutes to breathe clean, fresh air. I was in there long enough to get a little headache. I wouldn't normally worry about this, but I am 7 weeks pregnant. Could I have harmed my unborn baby by being in there for 5 minutes breathing in the strong propane?