Not likely due to the other drives other than perhaps heat (each drive adds about 10W of heat).
I would try and rebuild the array first as a hiccup may have caused this. This is well documented in the forums and wiki (
http://wiki.contribs.org/Raid); a search would have shown you how to rebuild and determine which disk failed.
I would also ensure the box is well ventilated as heat can cause a temporary glitch throwing a disk out of the array. consider also the ambient temperature of the room.
If the same disk fails later or the array won't rebuild then either you have a real heat or connection issue (to be rectified) or of course a bad disk and it should be replaced ideally with the same make/model.
In my history I have had a failed disk once. I have also had a disk thrown out of the array for no apparent reason and after rebuilding the array, all has been fine for almost two years.