Yes, it could definetly be a response to the medication. It is a known side effect.
I cannot tell you for sure, but I can tell you that I have tried several anti-depressants and while taking them I had high blood pressure. It was severe enough that my insurance company sent me a letter regarding how to get it under control. Do not switch to Effexor... bad, bad stuff. Read the forum on the Effexor and see how many symptoms people have that are no where to be found on the "clinical trail symptom's list".