Trouble finding the right word

i sometimes have problems finding the right word when talking. For example today i was talking to a friend about seeing someone at Mcdonalds. i said to her 'we were sitting in the (here i couldnt find the word 'playground' i could even picture the place in my head where i was trying to explian but i couldnt get the word. I did but it took a few minutes) this worries me, and it happens quite often. is it something i should worry about?