What is the meaning of "Hitztayadnu"?
Rashi: This is from the root Tzedah, when we took provisions for the road.
They said that they took hot bread [and moist, from the oven], and now it is dry and Nekudim. If they took much bread for a long trip, even if it was exposed, surely loaves touched each other. It should have become moldy (like we say about Lechem ha'Panim; refer to Shemos 25:29:3:1***)!
Radak: Indeed, Nekudim is moldy bread, which has red, yellow or black dots. 1
Perhaps Yisrael assumed that they had special holders to hold the loaves separate (like those for Lechem ha'Panim, perhaps on many donkeys). Or, they took a kind of bread prone to dry out and not get moldy, especially if they traveled through a hot, dry climate (e.g. the Sahara desert). However, if so, how does the dry bread prove that they have been traveling such a long time? Perhaps Yisrael believed that they want to become Ovdei Hashem (refer to 9:9:1:1), and feared to ask too many questions, lest they be offended and return to be idolaters. (PF)
Normal bread gets moldy within a week or so. After a month it is totally inedible. If they traveled as far as they claimed, what did they eat after this? If they had also proper food or money to buy food, why would they keep inedible moldy bread? Would they anticipate that Yisrael will suspect them, and require a proof of their origin?! If they took toasted bread, or hard crackers (refer to 9:5:1:1,2), it might start getting moldy now