I was thinking that the feed store personnel should have known better and said something since you were buying chick supplies. Unfortunately, most employees just want to ring you up and make the sale. I've been reading accounts like this more than I like to see. Anyway, no harm done. I'm not...
Yes! Cedar shavings emit a dangerous fume that can kill your chicks! Remove them quickly and go back to paper towels until you get the pine shavings! You are probably OK, so don't panic, but just don't leave those cedar shavings in there.
Don't let them eat too much of it. If necessary, put the paper toweling down over it. You won't need chick grit until you feed them anything other than the chick feed. If you can find it, buy premium large flake pine shavings at your feed store. My feed store sells a cheaper bale of pine...