Dog going to the toilet in the house!

Hi all - been awhile since i've been on here just due to work being busy and we are in the throws of planning a wedding Anywho basically I am looking for some help and advice and here is the back story.
Within the last week/10 days Bailey (who is 5) has eliminated in the house twice (to include urine and stool) the first time we awoke to find this on the kitchen floor - sure we were mad (didn't punish him as we didn't catch him in the act) and i blamed myself - maybe he should have been let out the back longer before being put to bed but I did his usual routine and let him out as normal so couldn't understand why he went again during the night and in the house as he hasn't done this since he was an 8 week old pup! so I put it down to me not letting him out (even though I did) and just a once off accident but low and below he has done it again - nothing has interrupted his usual routine of feeding/play/ or going to the toilet which is always the same - I let him out usually at 12, he does his business and then he sleeps in the kitchen for the night and then out again first thing - Maybe I'm over-reacting and it's just a case of more toilet breaks but this is so out of character - and I have checked his waste and doesn't look as if there anything wrong (as in no worms or things like that) so I suppose I am asking anybody encounter this or have any ideas on what could be going on.