I own an 05 F-150 FX4. I have put 31,000 miles on it. Every once in a while I would fell the transmission shutter a little when changing out of 1st into 2nd. Started noticing this around 26,000 miles or so. It wouldn't do it all the time just sometimes. I just thought it was normal since it is a fairly new truck. Well, the other day it actually slipped pretty good when changing to 2nd. I made it home and checked the trans fluid. The dipstick was dry! So I added some mercon V until it was right. It ended up being half a quart low. I drove it and rechecked it again. Dead on the money. It hasn't slipped again...think goodness. So my questions are....

I know the trans system holds a total of 14 quarts, how could the dipstick be dry if its only half a quart low? Would half a quart make it slip? Is it that sensitive?

Should a truck with only 31,000 miles be using transmission fluid like that? There are no leaks at all. I'm thinking it wasn't filled to the correct level from the factory or at least I'm hoping.

Also, do you think any damage resulted to my transmission due to this misfortune?

Thanks