thermodynamics - Are the vibrational modes of CO2 active at room temperature?

I was doing an experiment whereby I had to measure the specific heat ratios of certain gases. Carbon dioxide came out to be around 1.3, and checking with the accepted values this is close. My question is, the only way I can justify this answer is if $\ce{CO2}$ had 7 active degrees of freedom at room temperature. This implies that the molecule is vibrating. I am not a chemist and I thought that molecules only store energy in this degree of freedom at high temperatures.