I would hazard a guess that he is just bored. At four months they are going through a major developmental growth spurt...he has just realised that there is more to his world than his mobile mat, LOL. Maybe get down on the floor with him and introduce some new toys,shapes and noises. At this age they need lots of attention and are very time consuming, but it will pass. He will soon be more mobile and will be able to occupy himself for a little longer.
Enjoy your time playing with him and forget the housework for a little while.
This too shall pass.