There are days when my cats have done this....do not want to eat and even the foamy vomit you describe. Sometimes they have a hairball yet most times it is nothing. But, I would say not to worry today - but just keep an eye on her and if it keeps up or gets worse, then a call to the vet would be a good idea. It could be like Lorraine said - a change in her diet or the stress of a new home - or one of many things. Like I said - my cats often have days like this and it has never amounted to anything but since she is new to you - just keep a close watch and try not to worry just yet - OK? (((HUGS)))

PS I LOVED your siggy and asked Kay for one almost like it