Oil Change

Ok i done the oil change but i left the old oil filter, it had 10000k's on it is there any problem with that does the oil filter last another 10000k's or should i change it now i know that i should of change it @ the same time has the oil but has i dont race its a daily driven car i left it out, i went to 2 mecanics and they said that it should be ok has the filter is the original Honda 1, could any one give me there opinion because these mecanics are are not specific Honda mecanics, im planing on changing my oil and filter but the oil only has 2000k's, the oil i used is Castrol GTX Magnatech 10w 40 i fild it up between the 2 holes on the stick, i keep on cheking the level every week and its just a bit darker because of the oil that was in the filter any help apreciated