Snowmobile low on coolant. Should I be worried?

I have a 2010 arctic cat crossfire 800 and this year I was doing lots of trail riding. The overheat light came on 4 or 5 times over the winter. So this summer I went to fire it up and I noticed that there was no coolant in the resovoir. I opened the rad cap and looked inside and seen that the level was right where the resovoir turns into the tube, right at the bottom. My question is should I be worried of air in the lines?

Naah you should be OK,,,,,,,,,,,,,,,,,,,,,,,,,,

ADD ANTI-FREEZE 50/50,,Check for leaks and test anti-freeze with a gauge,,you can buy at gas station or auto parts store and no don't worry about air,,let idle till hot then top off with anti-freeze...