I Have Twice This Week Had A Very Strange Almost

I have twice this week had a very strange almost floating off balance feeling while sitting down.
I am very athletic and in shape so this has thrown me a little for a loop. I almost feel like its a dream..floating for just a few seconds then it dissipates. no other symptoms...although my vision is somewhat blurry.
I feel fine just have had these two occurrences and its strange to me.