A week ago I had a seizure and the neuro doctor diagnoised me with astrocytoma, should I be concerned?

Likely cause of sz. You need to see a neurosurgeon and uncover the extent of your tumor. These can be evolving types of problems, and this needs careful management and decisions to assure a stable future. An oncologist may be of assistance. If this is indeed, a glioma, might consider complete removal, if possible. You should definitely be on anti-seizure medication. Hope all turns out well.