Yes, my tinnitus which is usually not to bad, can sometimes get worse after an MRI. It becomes louder and usually reverts back to it's normal level within 3 or 4 hours. I try and use good ear plugs which does help.
Just a side note regarding MRI's - I posted a question quite a while ago. I had experienced terrible pressure within my head towards the end of one of my first MRI's and wondered if anyone else had that experience. Know one here could explain where the pressure feeling would come from. I had a follow up MRI and questioned the tech about it. She asked me where I usually put my arms. I told her I like to clasp my hands over my stomach. She said clasping my hands would cause "arching" which may have been the cause, and recommended keeping my hands at my sides. Since doing this I've not had any issues with pressure in my head during MRI's.
Hope your tinnitus calms down for you.