My son did the same thing, when we moved him to a crib at 3 months he would always end up in the corner with his little head smushed up against the wooden slats, it drove me nuts, I was worried he'd damage his brain through his soft spot or something! My doctor said it was fine and not to worry abou tit, and told me not to use bumpers. The risk for SIDS is up to one year (not 3 months, as someone else posted, though I think the risk decreases as time goes on, and as someone else says, the research seems to be suggesting now that SIDS deaths might be due to a glitch in the brains of those babies that doesn;t startle them when they aren't getting enough oxygen, so they don;t adjust like most babies do). My son in ten months old now and still smushes his head up in the corner half the time, it's never been a problem. good luck!