In a current commercial ad of bird's nest aired by China's National Radio, two women identified as former classmates had the following conversation:
甲:我妈快70岁了,我要买礼物回去过中秋。
乙:是呀,好久都没见到咱妈了。。。。
It is clearly the two speakers are not sisters or daughters of the same woman which they both call mother, but 我 and 咱 are both first person nouns, what is the relation of the two words? Does one of the speaker try to endear herself to the other?