1 - Your bitcoin in the Slush pool = no lost for you.
Slush have a nice system to keep most BTC offline, so if lost occurs, he will be able to refund from his pocket, as he stated earlier !
2 - No need to change pool : mining on stratum.bitcoin.cz is safe.
Imo, no problem at all.. Slush is fast to respond to emergency, professional and trustworthy pool operator who communicate with users.
Slush first post I know about it :
https://bt.irlbtc.com/view/1976.msg1925445#msg1925445Other following Slush post confirm we are all fine mining there
