I've been noticing it every once in a while for the past several years, but now that I have all those babies growing and going blue every three to four weeks, I am hitting a lot of them when they are blue, but I can't tell. So they gobble down their mouse and puke it back up a couple days later. I am so serious about avoiding it that if someone hasn't shed in the last month, they aren't getting fed. If someone hasn't pooped since the last feeding (which I know by a huge weight gain) they aren't getting fed. I check every single baby before thawing mice for them. I am sick and tired of it. And it really became noticeable back in September- I think Foxy was the first one to regurge when blue, and then every once in a while, one baby per feeding, even WITH me trying to be super-vigilant, someone would slip through when they were clear, or in that dirty phase before they relly go blue, and I'd get another regurge. It was nice and warm then, and really is never colder than 65 in my house, anyway.