According to research, bread can become moldy if it is not stored properly. Two of the big agents in the molding of bread is, exposure to air and being stored in warm, moist environments.

We learn from the Bible that bread is a type of the word of God (see Deuteronomy 8:3And he humbled thee, and suffered thee to hunger, and fed thee with manna, which thou knewest not, neither did thy fathers know; that he might make thee know that man doth not live by bread only, but by every word that proceedeth out of the mouth of the LORD doth man live.
See All...; Isaiah 55:10For as the rain cometh down, and the snow from heaven, and returneth not thither, but watereth the earth, and maketh it bring forth and bud, that it may give seed to the sower, and bread to the eater:
See All...; and Matthew 4:4But he answered and said, It is written, Man shall not live by bread alone, but by every word that proceedeth out of the mouth of God.
See All...). So, if bread is a type of the word of God, perhaps we should watch out for agents that would work to mold or corrupt the word of God.

The first molding agent that was mentioned is that of air penetrating into the bread. Air penetrates through openings or gaps. Does your Bible have any holes in it? Say, like verses missing? Most of the new versions have left out approximately 17 verses. Does your Bible have Matthew 18:11For the Son of man is come to save that which was lost.
See All...? Maybe it has the verse, but check the footnotes. Does it have a note saying that this verse does not belong? The absence of this verse as well as the other 16 might be holes that would cause your bread to be moldy.

The second molding agent that was mentioned is improper storage. Is it possible that the bread you hold in your hand has had some improper storage in warm, moist conditions. It is stated by Bible believers and modern version defenders alike that the Sinaiticus, which is one of the main manuscripts used for the production of modern versions, was found in a can that contained trash waiting to be burned. Sounds like a warm, moist environment that could cause the bread to become moldy.

Joshua would have done well not to make league with those carrying the moldy bread (see Joshua 9:1-6 [1] And it came to pass, when all the kings which were on this side Jordan, in the hills, and in the valleys, and in all the coasts of the great sea over against Lebanon, the Hittite, and the Amorite, the Canaanite, the Perizzite, the Hivite, and the Jebusite, heard thereof; [2] That they gathered themselves together, to fight with Joshua and with Israel, with one accord. [3] And when the inhabitants of Gibeon heard what Joshua had done unto Jericho and to Ai, [4] They did work wilily, and went and made as if they had been ambassadors, and took old sacks upon their asses, and wine bottles, old, and rent, and bound up; [5] And old shoes and clouted upon their feet, and old garments upon them; and all the bread of their provision was dry and mouldy. [6] And they went to Joshua unto the camp at Gilgal, and said unto him, and to the men of Israel, We be come from a far country: now therefore make ye a league with us.
See All...) and perhaps we should learn from his mistake.