I had the same issue crop up. I changed my userdate function. Seemed the $_SESSION variable was empty for my timezone and daylight savings offset.
OLD function
function userdate($format,$gmtime) {
return Format:($format,$gmtime,$_SESSION,$_SESSION);
}
NEW function
function userdate($format,$gmtime) {
global $cfg;
return Format:($format,$gmtime,$cfg->getTZOffset(),$cfg->observeDaylightSaving());
}