4yr old craving attention after visitation

I have a 4yr old who's father has been in out and out of his life for the past 1yr. and prior to that, he was nonexistent. I've been remarried for the past 2 yrs and he calls him "dad". for the past 6 months, off and on, my son has been doing every other weekend visits w/ his biological father who lives 2hrs from us. When my son returns home, he is very "clingy". He will not sleep in his own bed and will cry for hours if made to. He will stay up talking nonstop for hours after every visit and need lots of hugs/kisses. This behavior usually continues for a 2-3 days then he will go back to sleeping in his own room and playing with the other kids. Is this normal adjusting after 6months?

[mammo]

I would be concerned.  You have to wonder how he is being treated while at his father's to need all this reassurance that he is loved.  Try talking to him about his visits with his father, ask what they did, did he have fun, etc.  If your son acts like he doesn''t want to go with his father, then I would want to know why.  The hugging and kissing may just be that he missed you, but not sleeping in his bed, and for this to go on for days is of concern.  Just make sure the two of you talk a lot about his visits, and you may pick up a clue as to why he acts this way afterwards.