You might want to check these two over for any health issues just in case they have something that is causing them to be a bit lethargic. Possibly they feel threatened or maybe got scared of something out in the field.
As long as they are eating, drinking, laying eggs and acting healthy in every other way, then it may be just a passing thing and eventually they will get back to free ranging.
Welcome to BYC!
I'm new to BYC too so I'm not the best to answer but from my experience just make sure u see them eating and drinking. U can try giving them a tasty treat to get everyone attention. To check a chicken over for health just make sure they r not limping check for feather lose, make sure there combs are a healthy red color eyes look clear they are not sneezing it anything like that. Hope this helps. Also remember in new to this too so hopefully some others will post too.
Also I would only seperate them if u are concerned or haven't seen them eat. This way u can monitor there eating or if u notice one of the things I listed above
Some chickens are just lazy also, if their food is in the coop they may not feel a real need to go find more. Also chickens that are going to lay an egg that day, often tend to hang around the coop until they have laid it.
Thanks guys, today the two stragglers came out of the coop for a couple hours, there combs are pinkish red,asvis there wattles. However I have noticed a single feather on the floor of the coop today. But other than that they seem normal. Thanks again for all the responses.