Desco was just flying around like she normally does when she saw Miss Nano and decided to follow her.

She does that.

She sets down behind Nano with an audible thump - not something she usually does, but she still can't speak and it serves as a way of alerting Miss Nano - and reabsorbs Usatako into her back before trotting up behind Nano and greeting her with a raised pad of paper.

Hello, Miss Nano! Desco is here!