I usually tie my shirts very tightly and am afraid if I tied them wet, they wouldn't dry all the way through and might sour if I left it too long.
I guess if you left them for a really long time, and they didn't dry, you might have a problem. My experience is that I can leave them for about 2 days before dyeing, and they aren't really wet but they haven't dried totally. There is a whole school of thought on wet vs dry before dyeing! Steve, our forum host, likes his shirts to be bone-dry before applying the dyes. I have morphed into liking the shirts damp from the soda soak, but not too wet, and not bone dry. Also, I damp fold/tie before soaking in the soda ash solution to protect my hands... I tend to have skin that is sensitive to the soda ash, and don't like trying to fold with gloves on. Dyeing is such a forgiving art...