My husband does not recognize me, is this a transient thing?

First, do not take this personally!

Yes. It may not be all the time. My mom would not recognize me as her daughter, thought I was her sister, often. Often did not recognize her husband and wanted him to leave.

Hang on, it is likely to get worse.

My mom went from knowing my name and how I was related to her to not knowing my name. However, she seemed to know that I loved her and that I cared for her. She was glad to see me but could not call my name. That was the case until she died. As the phases of this disease progress, you have to adjust your expectations. It is incredibly hard. I was upset she did not know me but glad that the mother/daughter bond was never lost. I did not try to get her to remember. I just tried to meet her where she was in the disease.

The same would happen to me with my Husband.
We would be in the store and he would start to follow someone. I figured by the look of the person he may have thought it was me in my 20's (long brown hair)
sometimes he would follow someone with gray hair and a bit more heavy set and I figured he was thinking it was me in my 40's. I had gotten my hair cut and stopped coloring it and I was just waiting for the time he would follow a gray haired old man! that never happened...
We were also in the store one day and he got a panic look on his face and I asked him what was wrong and he said he had to find his wife. I told him I would walk with him until we found her. I left my cart of things and as we walked out toward the car I unlocked the door, and he walker right up the car, put his walker aside and opened the door.
As I explain all this the only time he spoke was the one time he said he was looking for his wife. Other than that he was pretty much non verbal. Probably had not put more than 2 sentences together in 6 years. If he spoke it would be 1 word.

What you can do..
Let it go.
do not try to convince him you are his wife.
Sometimes if you leave the room then come back into the room that might "reset" his recollection. You could try saying.."You are right, Ann would like this let me go get her" Leave the room then come back and see what happens.

But I would figure that this is another phase, another part of his decline.

I am so sorry, once this happens and lasts for a month or two it is unlikely to go away with the exception of briefly here and there. So that is to say there will be episodes in which he does fully know you. Those are lucky times. Most dementias follow a slow and steady downward trajectory without any improvement. Some very few types have a bit of come and go, up and down for some periods, such as Lewy's. This is one of the saddest things, that we do lose them while they are still living. Again, I am so very very sorry. As a nurse I witnessed this over and over again. People--families--often adapt to it with some time. But at first it is a dreadful shock and disappointment.