Problem ?

My cat is acting out of character, is something wrong ?

Yes there could well be something wrong. Changes of behaviour are often an external indication of physical or psychological issues. Changes in eating or drinking, changes in activity levels, changes in social interaction, the development of aggression or hiding away could all be signs that something is amiss. You should first consult your vet to check that there are no physical problems: he or she should be able to refer you to a qualified behaviourist if the change appears to have a psychological origin.