No, not common on any gas engine, or the 3.0l
Keep track of the MPG, you should expect the high teens low 20's
Could have been running rich for awhile so you have some carbon build up in the cylinders.
Pull a spark plug or two and have a look at the tips.
In any case run some Seafoam in the gas tank, it will clean up the fuel system and maybe clean off a bit of carbon.
Leaking valve guide seals are usually noticed when, after idling, you get a puff of smoke when you give it gas.
But keep track of the oil level, it was low so it could be using oil