Should i follow up on this...?

There is no magic way to find out what the real reason for your being let go if your boss doesn't tell you the truth. On the other hand your boss may have told you the real reason and you can't believe it because you have a different perception of the situation. Either way there is little you can do. If you have some friends who work there you may talk to them and ask them what they have heard. Although this is risky as sometimes just get more misinformation. The fact that your boss put out an e-mail saying you want to pursue other interests indicates that they do not want to damage your work record. Perhaps you should wait a few days to let everyone emotions settle down and give your boss a call and ask what kind of a reference they would give you if a prospective employer were to check. Although you expressed willingness to work more more hours it is your attitude and performance while you are at work that count the most. Good luck The PracticaL Mentor