I think it's normal. My son was the same way at that age and by 10 months he was only having 16-20 oz of formula a day and also pretty picky with his solids. My son was I think eating the stage 2 dinners at that time and he still had to have pretty mushy food or he would start to choke.
They are so interested in other things at this age, like learning to walk and exploring their world the last thing they want is to be stuck in a highchair eating.
As long as your son is healthy and his weight gain is good I wouldn't worry. You could mention it to his doctor at his one year check-up.