I am an expressing newbie, so forgive me for the silly questions I may ask lol!

Last night I managed to get 50ml and after expressing put it straight in the fridge in an air tight container. I've just gone to get it out of the fridge to add the other 50ml I just expressed to it and the milk I expressed last night looks, well, a little curdled I guess. All the "fatty" bits are sitting at the top of the milk. This isn't normal is it? Not sure what I did wrong?

Also, is it ok to be adding ebm to previous ebm in a 24 hour period?

Any help would be appreciated!

Thanks!