I've never heard of one cracking, and the one on mine is solid as a rock. But manufacturing defects do happen. The aluminum may have been poured wrong. It would be covered under Ego's five-year warranty. Give Customer Service a call (and make sure your tool is registered if it isn't already, to help speed along the process).
CS can be reached at 1-855-EGO-5656 (1-855-346-5656) from 8:30AM - 8:00PM EST (Monday - Friday) & 10:00AM - 6:00PM EST (Saturday & Sunday).